I'd not been having any trouble with pdf's for a while but suddenly no
recent pdf's show a thumbnail, just an Adobe logo. I've got Master pdf
and the simpler Evince (for when I just want to read something.)
In the past, if this happened, all I had to do was change the file name
and then a thumbnail would appear. That doesn't work here.
(I think I've asked a similar question before but on hunting through the
archive couldn't see a clear answer.)
Bev