Bug in group channel or my wrong

There is a problem that I think my friends report and may be resolved until it’s gone and I decided to report myself.
When I want to connect several of my audio channels to a group channel (pressing Command + Shift and Click on PC and Control + shift & Click In PC), the sound will suddenly be muted and my stereo channel will be deleted.
Even from audio connectivity settings, I can not create a stereo channel before, and the new channel must be new.
This problem does not occur when the project starts, and when the project gets heavier, it always happens
This problem also exists in PC version

Hi and welcome,

I’m sorry, I’m not sure I can understand the issue completely. Could you maybe write a step-by-step reproduction? Or could you make a video?

Could you try in Cubase Safe Start Mode, please?