The automation of the bypass of stomp effects in the Amplitube 5 plugin doesn’t work in Cubase 14.0.10. It is written but ignored by Cubase. The automation of other parameters works.
Bypass automation of stomp effects works in Ableton Live 12 with Amplitube 5.
Bypass automation of stomp effects works with Amplitube 4 in Cubase.
Your point about it working in Ableton wasn’t enough of a hint by itself, since - at least in theory - your Ableton project might have used the VST2 version of the same plugin, while Cubase 14 is likely to use the VST3 version. – So your confirmation, , that both Ableton and Cubase are using the VST3 version is a meaningful piece of info.
Also: I’m not questioning your experience or the severity of the bug. I’m merely trying to help pinpoint the exact circumstance of the bug.
While I’m just another user, I know enough, that bugs that can be easily and reliably reproduced tend to get fixed faster.