Spreadsheet loses some text formatting when copy/pasting from .rtf

I accidentally updated LibreOffice (NEVER DO THIS if you want things to continue working!) and now have version on Ubuntu.
The previous behaviour was that if I selected and copied text from an .rtf in Libre Office Writer, both fonts and font sizing of the copied text would carry across to LibreOffice Calc. The text would occupy one cell or multiple depending on whether the .rtf contained CR or CR/LF.

Now when I paste, the text loses its font sizing (everything gets sized to 10 points), but retains the fonts.
I have also tried Edit | Paste Special | Paste Special | Rich Text Formatting (the alternatives to Rich Text Formatting do something different which I don’t want)

I am assuming this is a bug, since it started when I updated. However, LibreOffice’s UI is so unintuitve and makes so many weird assumptions, I can’t tell if this is a a ‘feature’. Perhaps I there is a setting hidden away somewhere like ‘Always override text sizing’ and this got set by default when updating?

Help! Any pointers welcome!