Issues with iMac recognizing external hard drive all of a sudden...
I've tried researching this issue for a couple of hours and have had no luck (or am not tech savvy enough to trust myself trying some of the recommended fixes from random websites).
Short(ish) version:
After contacting Apple Support in a panic because my computer (iMac, 24-inch, M1, 2021, 16GB) wouldn't boot up (black screen with colorful circle in upper left corner) and also wouldn't boot up in recovery mode. As she was having me try recovery mode again, I mentioned I have an external hard drive (Toshiba Canvio Flex 1TB) plugged in that I strictly use for Time Machine backup. She had me unplug that.... I was then able to boot up just fine and everything was working as it should.
Now I have tried Disk Utility in order to see what mess I could get into there...As long as this external hard drive is plugged in, Disk Utility just says "Loading disks". As soon as I unplug the hard drive, my internal hard drive information promptly displays.
Also, Time Machine says it hasn't backed up in a week or so and that it will back up when my external hard drive is connected (even when it is, in fact, connected).
I was able to get Disk Utility to show the external hard drive ONCE. I just left it on "Loading discs" and came back a while later to it showing. I have since tried this (for hours) and have no been successful. I have also tried a different port and a different cord.
Longer story details (not sure of their relevance):
The issue started when I went to use my scanner (Canon R40). I clicked the "Start" button and nothing happened. This has not been that unusual since I got this Mac. But I can always go into the "CaptureOneTouch" app on the computer and start scanning this way. However, this time I got an error message stating an issue with the drivers. Again, not that unusual with this scanner and Mac. Went to try downloading updated drivers and restart computer....the unable to reboot issue started.