Preview, reduce file size, increasing the file size (Big Sur)

Hi All,

Wondering if you can help, I upgraded to Big Sur just last Monday I believe and since then my Preview programme is enlarging the file sizes of the PDFs I am exporting.

I work in media production and we use this feature quite a bit to reduce PDF sizes for many different documents like callsheets and storyboards. It was working fine on Catalina but when I used it straight away after updating to Big Sur the files have just jumped in size and will not reduce further.

I did a bit of troubleshooting myself online and I saw that ColorSync Utility is linked to Preview and that I could make custom export settings but this too doesn't seem to be holding. When I go to Filters, make a copy of Reduce File Size and customize it to reduce the file size further, then save this as a preset, leave the programme I find that none of my presets have saved and they've all reverted back to the initial default presets which in turn is increasing the file size of my PDFs.

Is this something that has popped up for people since upgrading to Big Sur? Is there a way to revert back to Catalina even? It's a feature that I use quite regularly so I would need this resolved ASAP if anyone can help.

Many thanks.