Hi,
Does anyone know what causes the function bar to grey out/disable.
More importantly how to stop it happening?

This is a problem that keeps randomly happening, there doesn't appear to be any rhyme or reason to what causes it and it occurs in both Standard PowerApps and PowerApps for Teams environments. The problem happens irrespective of there being code already saved and equally applies to labels with just text.
For established apps I've previously put the problem down to app updates since the last save and either turning settings off and on or coming back to the app after a day seems to unlock it.
However, a brand new app I was working on yesterday has opened this morning with the same issue (see screenshot).
Any clues on how to stop this happening?