Been having this issue (blank character sheet) since early November. I notified Roll20 then and was told that my issue had been submitted in order for a fix to be issued (hopefully, the fix that Nora C. referenced will be coming soon). Here, however, is what I've noticed about this bug: 1. It only happens with characters made through Character Builder. Per my tests, a character created directly won't have this issue. 2. It primarily (but apparently not exclusively) seems to happen when one misses a step in the character building process. I noticed that some of my Character Builder-built characters were having this issue and others weren't, and it seemed to correlate to whether or not I skipped some fields (like tags) for my NPC. Regardless, I hope there's a fix on the way for this soon, as it's a real bummer to create these NPCs and then, at the very end, have them be completely unusable. I have 7 NPCs that I spent hours making only to have to make them again because they were unusable.