ExFAT drive not mounting after not ejecting it properly
If your ExFAT drive is not mounting, here is the solution.
Open the Terminal:
sudo pkill -f fsck
fsck was holding the disk hostage. A quick `ps aux | grep fsck` revealed that indeed it was hijacking the disk/volume as soon as it was plugged in. `sudo pkill -f fsck` (or just `kill` with the PID if you prefer) immediately allowed the volume to be mounted.