Can't eject my Time Machine backup SSD

Sometimes when I open my laptop, I see a notification that my TM backup SSD was not elect properly. It is still physically mounted and Finder still recognizes it as mounted. The problem then becomes that I can't eject it. It stalls my restarts and I have to force it to shut down by holding the power button. When it wakes up, the problem is gone, but it soon returns with another notification. I decided I will start fresh and erase the disk, but since it can't be unmounted, Disk Utility is stuck loading.