Tooltip sentence mode overrides help tooltip content

When the tooltip is set to "Sentence format only" in the Format pane, the help tooltip (shown when clicking the question mark icon in the visual header) no longer displays its configured text. Instead, it shows the raw sentence template without the field values resolved.

Expected behavior:

The sentence tooltip and the help tooltip should function independently. The sentence tooltip should appear on data point hover, while the help tooltip should display its configured text when the question mark icon is clicked.

Actual behavior:

With "Sentence format only" enabled, clicking the question mark icon shows the sentence template text (with unresolved field placeholders) instead of the help tooltip content. The help tooltip text is effectively inaccessible to report viewers.

Steps to reproduce:

1. Add a line chart with a measure on the Y-axis and a date field on the X-axis
2. In Format pane → Tooltips, set Type to "Sentence format only" and enter a sentence with field references
3. In Format pane → Header icons → Help tooltip, enter a description text
4. In the report view, click the question mark icon on the visual header

Result: The sentence template is shown instead of the help tooltip text.

Power BI Desktop version: 2.155.756.0