Problem during gameplay on Aternos servers

During the game, when I try to place a block or an object on an interactive block, and I press Shift, it does not place it and it opens the interface of the block in question, which makes it impossible to put a sign on a chest, for example. I have tried with other services and even with a private world, and it only happens on the Aternos server. This problem did not happen before, until a few days ago I noticed it. Thanks