First - many thanks for your post Dexter_Lexia and Tasanar
We managed to get a bit more information about the situation in which the problem described appeared.
A few days ago, a group of 3 players went on a hunt for the Grizzle. They collected the required 5 scrolls , completed the required Bedlam quest, got a book, which they put on the altar (table) in the house, receiving in return three other books (keys).The player used one of the keys, and the window confirming the transition to the peerless popped out (it requires pressing OK to teleport).From the group of three players, for two the window appeared and the third person probably did not (or did not manage to press OK) - a monster who was nearby killed it. From that moment there was a problem - players did not teleport (with the message described), as if the system was still waiting for a response from the third player who died when trying to accept the teleport to the boss.