I'm running it in a Docker container now and it seems to be working. Not sure why.
My server never has more than three players on it, none of whom use any kind of non-standard add-ons. But we are all in creative mode.
I'm guessing there's an issue in the inventory code. The latest version of BDS keeps inventory itself rather than trusting the client to do it. This is to prevent cheating. But it's definitely broken.
Exactly! I was running 1.16.40.02 and before that 1.16.1.02 with no issues at all. My server is on Digital Ocean.
Incidentally, BDS developers, I have a six-year-old here who is very, very sad.
BDS has been up and running since my previous comment. I don't know what makes the Docker container different from the native OS but it solves the problem.