I wished I could say that your info fixed it but it didn't.
I did the full access and this was the 2nd time I tried downloading the Catalina friendly Thumbnailer... In talking with Embrillance they gave me the same info and said some have gotten it to work but most are still struggling to get it to work with the new update...
It's sooo discouraging since I used Thumbnailer everyday.
I have always had Apples but the last updates on my phone, laptop and iMac have all brought problems to an otherwise smooth running machine.
I feel my husbands pain now as he runs windows. :(
Thank you Foxfith for trying I really appreciate it.