Server icons do not load properly (or the server is sending out the wrong image/something is messed up). The error in the game output is as follows:

OpenGL debug message, id=1281, source=API, type=ERROR, severity=HIGH, message=GL_INVALID_VALUE error generated. Invalid texture format.

Seems to be something to do with having the same icon file in the server folder as well as world folder.
Client restart is required to clear the issue after it occurs.