Problem with custom theme (JSON)

What I mean is, sometimes when Power BI updates happen, the structure of the JSON for the theming can change. If your custom theme doesn't match the new structure, you can run into these issues.

See gif below explaining what I mean about saving a built in theme.

You can now visually compare your custom theme JSON with the one saved.

See if there's anything obvious missing etc.

Here's the JSON from the theme in the gif...

{
    "name": "Innovate",
    "dataColors": [
        "#70B0E0",
        "#FCB714",
        "#2878BD",
        "#0EB194",
        "#108372",
        "#AF916D",
        "#C4B07B",
        "#F15628",
        "#6F9EDB",
        "#FEE266",
        "#5DA9FD",
        "#4AC5BB",
        "#35B895",
        "#B69087",
        "#B6A887",
        "#F48459",
        "#1D5C95",
        "#BDA750",
        "#4A82BB",
        "#168980",
        "#288A6F",
        "#A67668",
        "#7B6E4F",
        "#B54C25",
        "#164672",
        "#7E6F36",
        "#31567D",
        "#0F5C55",
        "#0D2E25",
        "#7B594F",
        "#524934",
        "#793418"
    ],
    "foreground": "#FFFFFF",
    "foregroundNeutralSecondary": "#D2D0CE",
    "foregroundNeutralTertiary": "#979593",
    "background": "#3a3a3a",
    "backgroundLight": "#3B3A39",
    "backgroundNeutral": "#605E5C",
    "tableAccent": "#2878BD",
    "maximum": "#2878BD",
    "center": "#FCB714",
    "minimum": "#D0E4F5",
    "hyperlink": "#2878BD",
    "visitedHyperlink": "#D0E4F5",
    "textClasses": {
        "callout": {
            "fontFace": "Arial",
            "color": "#FFFFFF"
        },
        "title": {
            "fontFace": "Arial",
            "color": "#FFFFFF"
        },
        "header": {
            "fontFace": "Arial",
            "color": "#FFFFFF"
        },
        "label": {
            "fontFace": "Arial",
            "color": "#FFFFFF"
        }
    },
    "visualStyles": {
        "*": {
            "*": {
                "background": [
                    {
                        "color": {
                            "solid": {
                                "color": "#3a3a3a"
                            }
                        }
                    }
                ],
                "visualHeader": [
                    {
                        "foreground": {
                            "solid": {
                                "color": "#FFFFFF"
                            }
                        },
                        "border": {
                            "solid": {
                                "color": "#3a3a3a"
                            }
                        },
                        "background": {
                            "solid": {
                                "color": "#3a3a3a"
                            }
                        }
                    }
                ],
                "outspacePane": [
                    {
                        "backgroundColor": {
                            "solid": {
                                "color": "#3a3a3a"
                            }
                        },
                        "foregroundColor": {
                            "solid": {
                                "color": "#FFFFFF"
                            }
                        },
                        "transparency": 0,
                        "border": true,
                        "borderColor": {
                            "solid": {
                                "color": "#979593"
                            }
                        }
                    }
                ],
                "filterCard": [
                    {
                        "$id": "Applied",
                        "transparency": 0,
                        "foregroundColor": {
                            "solid": {
                                "color": "#FFFFFF"
                            }
                        },
                        "backgroundColor": {
                            "solid": {
                                "color": "#605E5C"
                            }
                        },
                        "inputBoxColor": {
                            "solid": {
                                "color": "#605E5C"
                            }
                        },
                        "borderColor": {
                            "solid": {
                                "color": "#979593"
                            }
                        },
                        "border": true
                    },
                    {
                        "$id": "Available",
                        "transparency": 0,
                        "foregroundColor": {
                            "solid": {
                                "color": "#FFFFFF"
                            }
                        },
                        "backgroundColor": {
                            "solid": {
                                "color": "#3a3a3a"
                            }
                        },
                        "inputBoxColor": {
                            "solid": {
                                "color": "#3a3a3a"
                            }
                        },
                        "borderColor": {
                            "solid": {
                                "color": "#979593"
                            }
                        },
                        "border": true
                    }
                ]
            }
        },
        "slicer": {
            "*": {
                "items": [
                    {
                        "background": {
                            "solid": {
                                "color": "#3a3a3a"
                            }
                        }
                    }
                ],
                "numericInputStyle": [
                    {
                        "background": {
                            "solid": {
                                "color": "#3a3a3a"
                            }
                        }
                    }
                ]
            }
        },
        "keyDriversVisual": {
            "*": {
                "keyInfluencersVisual": [
                    {
                        "canvasColor": {
                            "solid": {
                                "color": "#3B3A39"
                            }
                        }
                    }
                ]
            }
        },
        "page": {
            "*": {
                "outspace": [
                    {
                        "color": {
                            "solid": {
                                "color": "#3a3a3a"
                            }
                        }
                    }
                ],
                "background": [
                    {
                        "transparency": 0
                    }
                ]
            }
        }
    }
}

If this doesn't work, you may just have to load your theme and then go into the 'Customize current theme' and change things one by one but at least that will work across all visuals in the report.