Deleted all crates and reinstalled SSL.
Everything working fine now.

It sounds like crates and database files were damaged when the drive was disconnected.

Glad to hear you got things sorted.

Is this a common problem in this sort of situation? I'm currently trying to reorganize my music collection at the moment and am debating whether to organize by a folder-->drag and drop into Serato method or simply attemping to properly tag everything and use crates exclusively.

Since my folders/files are still there and seem to be working properly (haven't tested enough tracks to know if the unplugging had any significant corruptive effect on my files), this seems to be the safer, more stable route to take.

Is what happened to me normal or a fluke incident?

Disconnecting an external drive while SSL is building overviews and etc can definitely result in potential file damage and file loss.

If you're using the external drive and disconnecting it from your computer properly, the chances of this problem happening again is very very slim.