2019-05-15, 18:46
Yes, the upgrade to LibreElec which contained Kodi 18.2 just came out on May 10th, so your method worked perfectly. It turned out that somehow, in the process of copying the database file to the SD card, it had become corrupted (Not a database). I will copy everything over using SSH from now on.
Thanks everyone for your help!
Thanks everyone for your help!