Dashcam not always recording during Sentry Mode

Don't know if this is a glitch or a common problem. My M3 is two months old with firmware 2019.12.1.2 installed. I have a 256Gb flash drive formatted and installed. It's been recording well.

Last night I parked in a public garage, engaged Sentry Mode and proceeded to a restaurant. During my meal, received alert (large Red Dot on Apple Watch ) that possibly someone was messing with my Tesla (proof Sentry Mode was infact engaged). It was dark when I returned to the car and fortunately saw no problems.

Wondering what had happened, I've just now reviewed my flash drive. There is No Recording for last night. There is a recording for previous day and also this morning but there should be a recording in between the two. (I also don't understand why there was a recording this morning when the car was parked in my garage and sentry mode not engaged)

I'm finding that recordings are somewhat haphazard. Some I get and others are missed and some I shouldn't be getting (like in my garage).

Do others have this problem and is there a fix for reliability? I still have about 186Gb available storage so space is not an issue.