My workaround is to comment "centovacast.callback_all" in centovacast.liq, then your custom callback_all function from custom.liq will work.
But if you will change your Auto-DJ configuration and restart it - all changes in centovacast.liq will be gone and you will have to comment these lines once again.
Apparently that should not happen, looks like a bug, either comments should be kept, or custom callbacks should work.