Count Column by Group and filter for all variable

A small update to my prior solution almost gets you there. (Swap out the hardcoded stage name with _CurrName.)

VAR _CurrPID   = 'Table2'[Project ID]
VAR _CurrIndex = 'Table2'[Index]
VAR _CurrName  = 'Table2'[Stage_Name]
VAR _SubTable_ =
    FILTER (
        'Table2',
        'Table2'[Project ID] = _CurrPID
            && 'Table2'[Index] >= _CurrIndex
            && 'Table2'[Stage_Name] = _CurrName
    )
RETURN
    COUNTROWS (
        FILTER (
            _SubTable_,
            VAR _Stage = 'Table2'[Stage_Name]
            VAR _NextName =
                LOOKUPVALUE (
                    'Table2'[Stage_Name],
                    'Table2'[Project ID], _CurrPID,
                    'Table2'[Index], Table2[Index] + 1
                )
            RETURN
                _NextName <> _CurrName
        )
    )

To get the blank rows for the repeats try something like this:

VAR _CurrPID = 'Table2'[Project ID]
VAR _CurrIndex = 'Table2'[Index]
VAR _CurrName = 'Table2'[Stage_Name]
VAR _SubTable_ =
    ADDCOLUMNS (
        FILTER (
            'Table2',
            'Table2'[Project ID] = _CurrPID
                && 'Table2'[Index] >= _CurrIndex
                && 'Table2'[Stage_Name] = _CurrName
        ),
        "NextName",
            LOOKUPVALUE (
                'Table2'[Stage_Name],
                'Table2'[Project ID], _CurrPID,
                'Table2'[Index], 'Table2'[Index] + 1
            )
    )
VAR _StageChanges_ = FILTER ( _SubTable_, [NextName] <> _CurrName )
VAR _IsRepeat = ISEMPTY ( FILTER ( _StageChanges_, [Index] = _CurrIndex ) )
RETURN
    IF ( _IsRepeat, BLANK (), COUNTROWS ( _StageChanges_ ) )