I tried to learn the Devour spell in Zoluren but he said I could not learn it there.
Assumed it was only taught in a specific spot so spent an hour traveling around. After they all said I couldnt learn it, I returned to Zoluren and tried it again. Still didn't work.
I thought what the hell, I'll try it a couple more times. It eventually worked, even using the same syntax. I have it in a log if you wish to see it.
TL;DR: I tried to learn Devour but he wouldn't teach me. Had to travel around and return to ask a few more times before he finally did suddenly.