Hi all,
Since you’ve already tried so many things without success, you might try restoring a Roon backup that was created before this September update:
Why I want to suggest this:
After restoring a backup created before September 26th, a number of problems previously unknown to me disappeared.
Since then everything has been working fine again, the delays and other oddities are gone.
However, my server runs on RockOS and I don’t know when the corresponding update for other systems was released.
In my case it was the update that introduced native support of Tailscale.
It might be worth a try.
Good luck.