Already received two answers to my tickets concerning this bug, but all useless.
Ended up writing to “GM Iduellophos”, who supplied me with a link to D2r, L-O-L:
“Again, and for the third time, please bring this issue to someone who has the knowledge and skills to fix it. Am I even chatting with a human, or is this AI?” …because it does look like useless AI answers.
(In our sad era, the words “knowledge and skills” sound so refreshing, don’t they?)
If that bug came up something like a month ago, my unexpert guess is they might have changed something in another game, which had system repercussions in D2 LOD. Could it be?