JPEG mainly, but every other format behaves the same. If I do contact sheets with 1 X 1, they are large enough, but then the caption information is truncated.
Like I said, the problem started when I was using PM4, and I guess when I installed PM5 it went in and imported what ever setting / error was there. They were baseball card sized proofs in PM4, and even smaller (postage stamp size) in PM5.