When trying to retrieve XP from the Killer Joe sometimes it'll give you 100% of a level without giving you the level, and then you won't be able to retrieve anymore XP until you gain/lose XP from another source.

Have you found a way to reproduce this? I had it once when doing the changes, but then it went away and I couldn't reproduce it.

I don't know how to reproduce it but it's happened to me twice already, I'll keep trying.

I got some good tips from the helpful people who hand out in our chat all day. This should fix it. (next build...)