After killing the boss, the block cannot be collected. This phenomenon occurs on the server, but not on the single machine

I made some changes in the latest version that should have fixed this - if they didn't, let me know and I'll look again.

By that, I'm assuming you mean that the warding on the structure is not going away? Does this happen consistently every time on dedicated servers?

In the meantime, you can use /ta ward clear while standing in the chunks of the spire to remove the warding manually.

Yes, I have tried in the server. Basically, all Eldritch Spires cannot break the protection of the structure after killing the boss, but the method you provide can still work.