The newest version (5.0.5-Beta) doesn't work with Bartender4. Let me know if you need anymore information.

Doesn't seem to work with Ion either. Or WeakAuras.

Doesn't work with default actionbars either.
Maybe a savedvariables reset is needed? (after backing up ofc)

Edit:
Yes. I backed up my saved variables then
/run OmniCC4Config = nil
/reload
and reconfigured, it works after that, it's a settings migration problem (or no migration implemented)

Edit2:
Scratch that, resetting variables allows it to load without errors but as soon as it tries to show a counter it errors out again.