crash to max zoom

Windows 10 Home 20H2 19042.1237
Audacity 3.0.4
Behringer Xenyx 1204 USB/USB Audio Codec

I have long experience using Audacity without bother. BUT twice recently have had a sudden crash, losing about 40mins recording with screen showing a flat line of dots - which turn out to be the individual sample points.
First time I was able manually to save a copy(AUP) but hadn’t figured out what was wrong with the screen - the copy was showing on max zoom. So not lost but well-disguised!
Second time I had saved the recording every 10mins but after the crash the saved file was 40 secs of silence, not 40mins of speech, and again showing as flatline dots.

Any ideas please?
Why the sudden jump to max zoom?
Why was the saved 40min mp3 copy, second time, lost? Overwritten by the crash?

Is that what you mean by “max zoom” (zoomed in all the way to single samples)?

May or may not be relevant, but to zoom to fit the project in the Audacity window, press “Ctrl + F” (zoom to fit)

Could you be accidentally pressing “Shift + Z” ?

Many thanks.

Yes to my meaning of max zoom. At the time (with a live session running) I didn’t figure out what I was seeing beyond the abrupt loss of what I was expecting to see! Our alternative is Audition on a different laptop, so recording restarted.

This query hasn’t produced a “yes, obviously is is…” response identifying known issues. FAQ picks up mp3 problems which I need to check. I don’t think it is a misop CNTL Z - I tend to use mouse control for most things apart from marker insertion.

So nothing obvious, just some more diagnostics required here!