Anyway, I reset the my personlised VP19 window layout in b636 rather than using the b550 layout. There was no adjustment track crash this time. Thank you @Yelandkeil .
I just tested this on desktop. Blank project with just 2 video tracks. Added the Adjustment Track. Crash.
I wasn't able to reproduce myself here. I am reusing layouts from 550, added 1 clip to 1 track and another to a second, added an adjustment layer and an Fx but no crash.