Theres is something weird with the black and white latency compensation.
1. route audio track to a second track insert IK's black or white comp.
2. flip phase of one track
3. hit black or white's own bypass switch
-> not completly cancelling audio
4. hit host's bypass switch -> full cancellation
(happens at least in reaper 3.76 32 bit)
EDIT: exactly 1 sample offset.