auto stop of audacity recording

I am using ubuntu 18.04 64 bits and audacity 2.3.3 provided by official ubuntu software resources.
I have used audacity previously without trouble with other version of ubuntu.
Presently when I am recording from my usb microphone my acoustic guitare , the recording stop at any time without touching any thing.
I disable " sound activated recording " the level of which being at -50 db.
software playthrough of input is ON
Detect dropouts is ON.

I looked the manual and forum but did not find any clear answer . Is any one ? some suggestion to
understand the problem ? I’s really annoying .
Thank you to help me to understand and overcome this problem.

I have the same problem (Manjaro 21.0, 64 bit, Audacity 2.4.1): Recording stops at any time (mostly within 8 minutes) when “software playthrough” is enabled.
Until now I found no solution except using ‘ocenaudio’ - here is the monitoring of the input signal full functional.

“Sound activated recording” is disabled by default. Might you have inadvertently enabled it instead?

Windows guy here. This thread looks similar and provides a possible solution: Can only record one track

Hmm… also, I wonder if a sample rate mismatch could cause this problem…