I went into the playerconfig files. The thing I wanted to look at opened up into a garbled mess.Unfortunately, it doesn't work with my current (wired) mouse or my wireless mouse. The weird thing is when i first started the game, it worked just fine. It was while playing that it suddenly stopped working. My scroll wheel works perfectly fine with literally everything else, just not this one game. I did double check any mapping software, and currently don't have anything set up.
No help there.
Went in game in an attempt to replicate your problem. I ended up messing around with the scroll wheel config. Changed it. Changed it back. I could no longer zoom with the camera, but I could still do so on the map, just like your problem.
I hit the 'Reset Default' button at the bottom left.
It returned to normal.