This is new (for me, at least) in C15 and I can’t find mention of it in the manual (very possible I’m just missing it…it’s a gigantic manual). It happens seemingly randomly, and it’s overriding all the CC that’s drawn in the lane:
Hi,
To me, it looks like you have drawn/written some MIDI CC Automation data (in the Automation Track).
Ah that was it, thank you! I never realized I could have it in the automation lanes until now, that’s actually fantastic for the way I work.