Funny, I just had a similar issue. For about 16 months my setup was fine. Then, about 3 weeks ago, DS started reporting 'timeout' and not sending alerts.
I have new very robust hardware so it simply cannot be related to that (dedicated PC built specifically for BI and BI alone that was custom built following all the guidelines on this forum, for about $2400.00. I have 15 cameras and CPU hangs around 5%-7%).
Anyway, my BI license had relapsed around this same time and some posts indicated that alerts went away when that expired. So I renewed my license - no change.
Then I versioned up BI to the latest: 5.5.6.21 but no joy.
Then I versioned up CPU DS from: 2021.02.1 to CPU 2022.01.1, and just like, that everything started working again and has so for the last two weeks.
Yes I restarted my machine, BI and Deepstack in parallel as well independently and in several combinations before versioning anything up on any software (we are talking about windows here!).
I reviewed the OS/BI logs for clues. Once I decided it was DS itself I tried to issue any command that would let me see if it was having a memory constrained issue, but my best guess after reading about that was that to perform such commands required me to deploy DS into a container. While I am technical and am a bit twiddler at work, I try to keep that crap at work if at all possible so chose not to pursue that route. In the end, the versioning up of DS seemed to do the trick for me.
Keeping my fingers crossed. Would really prefer to know root cause however. I did not know that BI was pivoting on what AI it recommends/supports.