Likely a parsing error.

I also noticed a several seconds long lag before ObjectiveOverlay updated after switching classes using /class. Most of the time it worked fine, and snappy, except when it didn't...

When I fix the parsing error, this all should be resolved. Also, I think some objectives do not get cleared when they reach x/x completion, so we need to handle that (for the objective manager, scoreboard could stay as wynn does it).

Parsing error most likely, happens quite frequently. Usually the problem is in scoreboard reconstruction.