Not a huge problem for me yet but my chat does not work in any servers. i would love any fix
as @Charles said, this is likely my fault, the fix for Cobalt Essentials was released 6 days ago, most of the reputable servers should be up to date by now, I know 2fast is, so if chat works there, it was my fault.
It could also be because that server has Cobalt Essentials, it is currently a bug where Cobalt mutes everybody on the server as soon as they join, keep in mind the mod and server resources are still in early stages and are not fully complete, we are working out the bugs 
Hello, it is likely that you need to keep the mouse over the input field or click and hold on it while typing. Unfortunately this is a known bug with the game itself.