Salutations!
I have figured out what the problem was - certain punctuation marks at the start of a Steam name (such as the > in >DINKY<Barbar) cause this issue. I have changed my steam name to no longer have this punctuation character at the start, and the chat worked normally. After leaving the game and changing the name back, the issue returned. As such I can confirm that this is indeed how this happens, and how to avoid it. Those with clan or other group tag incorporated into their names should be advised that some punctuation characters (I did not test them all) will cause issues with the chat displaying.
Thank you!