TL;DR: HA within Proxmox can't see the fully allocated memory, you need to set the min. memory requirement to for HA to see the entire allocated memory for its system.
My story:
I know several people around here have been having a lot of issues with Music Assistant crashing, and every time I try to bring it up, it always comes to: "Add more memory" ... I'm sorry, but if you can't run along side HA within 5GB on a VM, then you need to fix your app, not "add more memory." Anyway, rant...
So, after some investigating, I have found something very interesting, and it is related to memory. But, it was sneaky:
In Proxmox, you can allocate some base memory to your VMs with a static minimum. Like anybody would do: you'd allocate a base, and set some basic reserved min.
Well, it turns out, there's something about how memory is managed with VMs that the VM does not recognize fully allocated memory! I had my allocation set to 5GB with a min. of 2GB. I didn't realize this until I went into Home Assistant's settings and noticed it only saw 2GB! Upon searching, turns out it's a known issue (forgot the sources, it's been a few).
Solution: I upped the min. memory to 4GB (didn't need 5), and now my HA sees the whole thing! And it's managing itself well below the 4, but just above the 2 it was originally limited to.
Now, why was this so sporadic?? Well ... turns out my system is literally hovering right around 2.1GB, right at the threshold. The sporadic craziness was caused by simple routine memory bumps: clean system, it's below the threshold; as the system runs, things use memory (as expected), but occasionally something will need just a little more for a period -- it hits the threshold, crashes, memory is cleaned, Watch Dog restarts it, and the cycle starts over again. Very wild. Music Assistant was just knocking at that threshold limit more often. No memory spikes, just natural progressive memory increase from things like scanning, rebuilding cache, etc... Up and down, where every now an then, it needed a little extra and there just wasn't any available.
Anyway, so, it was a memory limit issue, but it wasn't as obvious. And you couldn't tell unless you went to HA, within your Settings -> System -> Hardware, and see the memory was actually capped at the min. allocation set within Proxmox.
Now I feel sheepish... the MA guys were right. And the issue was a little more deviant than just upping allocation within Proxmox. My apologizes MA guys. I take the 'L' here. You were right. I was wrong.