I don't know how to fix this nor can I find any other topics with this issue.
Other people can hear me, but I can't hear anyone else or even see the icon to say that they're talking.
How would one go about fixing this issue?
Most times i have seen this bug, is when Server is running like 1.2.4 and others have mumble 1.2.4 but you have 1.2.3, all can hear you but you cant hear them.
What version is server running?
What version is others running?
What version are you running?
Secondary, check Configure -> Settings -> Audio Output
Is Device on Default Output, if it is, click dropbox and choose your soundcard to output from there.