IR - comparison A/B not working

Hello guys

IR comparison is not working as you can see attached.

I’m using Version: B2 daily Apr 19 2018 (core 2 DailyBuild Apr 18 2018)
Cinema version: CINEMA 4D Studio R19.053 S

I get this every so often but unfortunately have never found a repeatable set of steps to make it happen. If anyone can come up with a scene with repeatable steps that always leads to this, that would be great!