Cue buttons not working properly while streaming

Hi there - despite following the same set up process as I have done previously (from these forums) with no issues - using Mac Book Pro, XDJ-RR and OBS/Blackhole set up to stream to Twitch - yesterday my headphone cues wouldn’t work properly - the master channel was leaking into the cue even when turned all the way to cue....the cue channel wouldn’t isolate - it was audible but not in isolation to the master. tried everything I could think of but couldn’t rectify it.

Any tips? Thanks Andy