I also have an issue with the thumbnailer but it only occurs using Nemo file browser and only when browsing SMB share folder:
https://bugs.launchpad.net/ubuntu/+source/evince/+bug/1834386
I also have an issue with the thumbnailer but it only occurs using Nemo file browser and only when browsing SMB share folder:
https:/ /bugs.launchpad .net/ubuntu/ +source/ evince/ +bug/1834386