Sleeping in a multiplayer game does not display the chat screen button, but when another players is near the sleepping players to show.

Here's a video to reproduce the bug.

AND

You should always be able to access the chat no matter if your playing alone or with friends. It is meaningless to hide the chat button at all, and in fact, in the latest version 1.21.50, the button may not be displayed in multiplaver situations due to bugs, even if you press the keyboard shortcut, which has caused great inconvenience. It is strongly recommended that the chat button in the sleep screen should be always displayed in the next version.