Going through a few rounds of troubleshooting with folks on the macOS community forum as well as Apple tech support regarding the SSD overheat issue has helped me determine the following things:
- Whatever this problem is, it’s uncommon; nobody else seems to have experienced it
- The enclosure itself isn’t to blame; it happens on both my Plugable USB 3.1gen2 and on my Sabrent dual-slot Thunderbolt enclosure
- The overheating is only happening on the Crucial 2TB NVMe stick (that normally lives in the USB enclosure); having just the PNY stick (which lives in the Thunderbolt enclosure) doesn’t overheat, moving the PNY stick to the USB enclosure doesn’t overheat, and the Thunderbolt enclosure only overheats if I have both the PNY and the Crucial stick in it
- The overheating stops if I unmount the drive but leave it electrically-connected
- Mounting the drive even under macOS Recovery causes the overheat to occur just as quickly
For now I’ve moved my most critical files from the Crucial stick to my older SATA drive (which isn’t having trouble) so I can continue to work on the things that I normally do on my desktop, and my studio laptop seems to be okay with the PNY+Thunderbolt combination so I don’t think Novembeat is at risk because of that, at least.
This does mean I won’t be able to work on music from my desktop computer in the meantime, and video editing will have to be direct to NAS, which is doable, just not ideal.
Hopefully this all gets sorted out in a macOS update.