Brown trouser moment

[happydays]

View attachment 39104

As I hope this picture explains- I don't believe that I could have set the controls to ATTI as the settings wouldn't have let me.
Would it have gone automatically if I had lost GPS or maybe some interrupted signal from nearby interference?

What would concern me with this screenshot is the lack of satellites. I see only 5 locked when this screenshot was taken. That's not enough to get GPS hold and might explain why you're drifting in and out of GPS / ATTI mode.