Spreadheet themes not working

I started a spreadsheet a couple of months ago and applied a theme to the table. I have now added a new sheet and changed the name of the original sheet. I may have updated LibreOffice in that time also.
Now when I try to apply a theme to the new table nothing happens. With some themes the background colour of the whole sheet changes but nothing affects the populated cells.

Version: (X86_64) / LibreOffice Community
Build ID: e19e193f88cd6c0525a17fb7a176ed8e6a3e2aa1
CPU threads: 8; OS: Windows 10.0 Build 19045; UI render: Skia/Raster; VCL: win
Locale: en-GB (en_GB); UI: en-GB
Calc: CL threaded

I’ve discovered I was using “AutoFormat Styles” on the first sheet. Still not sure why Spreadsheet Themes don’t work though.