Screen recorder doesnt record sound

[johnCforVTS]

Good evening,
I screen recorded a lot the past ponth ( and i ll keep it that way due to the coronavirus everyday video meetings ) and i noticed that almost half of those doenst have sound. All of them were recorded with do not disturb on ( nothing interrupted those meetings ) and i tried to play all those with a different media player or via my laptop but still no sound at all. Most of the no sound recordings were as such from the beggining and some few suddenly gone mute mid session!
( Its not related to the recent update... It was there before that too )
Any ideas on the cause of that or how to fix that?
Thanks in advance.

[johnCforVTS]

For the last week everything is fine! I have sound every time! Hope to keep working like that...

[chriswatson3]

I got the solution of some of my problem here. So thanks