I thinks https://forum.qt.io/topic/159836/starting-a-debug-session-hotkey-half-the-time-doesnt-work-have-to-go-into-the-menu mentions the same issue, but there is no feedback yet.

In my case, the Debug icon on the on the mode selector is fully green (so ready for starting debug) but the Debug main menu shows "Continue F5" and "Stop Debugger" even when the debugging session is finished (it was QtCreator that was debugged).

So it seems something is out of sync, probably related to QTCREATORBUG-32059.

The bug does not reproduce always, I'll try to add more information and logs the next time it happens.