Compatibility table refers to FixedHeaders 4.0.0:
https://datatables.net/download/compatibility
Change log [...]
2021-09-10: FixedHeader 4.0.0
Scrolling now fully supported with FixedHeader
RowGroup now fully supported with FixedHeader
Scroller now fully supported with FixedHeader
However the download builder provides FixedHeaders 3.2.0, and the documentation page on FixedHeaders still states the incompatibilities associated with version 3, erroneously referring to the compatibility table:
https://datatables.net/extensions/fixedheader/
Please note that FixedHeader is not currently compatible with tables that have the scrolling features of DataTables enabled >(scrollX / scrollY). Please refer to the compatibility table for full compatibility detail
If latest stable version is indeed 4.0.0, it should be provided by the download builder and the documentation on FixedHeaders should be updated.
If version 3.2.0 is the latest stable version, then the compatibility table page should be corrected to reflect the incompatibilities associated with that version, and not refer to 4.0.0.
Thank you!