I tried to mount a big iso file (113 GB) and it doesnt do anything, i tried multiple times. Look like it's working, but it shouldn't take too much time (Waited like 5 mins). I installed a 3rd party app that can mount iso files, and its worked like instantly. Windows could mount a smaller file, it was 5 gb size.
@iceBlade7 Even on the latest build 22000.120 large iso files cannot be mounted. I had to also install a 3rd part app for it. Take forever and doesn't do anything until you sign out then you will find out it has mounted it.