It didn’t actually show up in the list of libraries, that was my first thought, and that was when I ended up messing with libraryfolders.vdf. Just outright removing that external drive from there had Steam just restore it after a reboot. Removing all the entries from that drive at least stopped it warning me that the game was installed on a different drive.

I seem to have fixed the issue, for some reason the cloud sync was screwing with the installation and clearing out a file related to it fixed it. Thanks for the idea though, on the off-chance this comes up again - because I’m not likely to trust an SD card in it again - I’ll look into it

Yes, the card appears to be dead, I’m trying to install the game to the internal storage now and it won’t install