After completing the quest and using the full vial once, the phial remains as the empty version in my inventory no matter how long I wait. I have tried using the console command to add the full version to my inventory to no avail. Any clues how to fix this. (On PC, of course).

Did you delete the empty version before using additem to add a full version?

Also, did you make sure to spawn the same version as the type you chose for a quest reward?

No idea why it isn't refilling correctly in the first place - do you have mods installed?

I forgot about having to input the number of items to add in the additem command. Adding the item works, however, it still does not refill. Removing the empty vial also does not fix the problem (full vial is consumed and no empty vial spawns). I have disabled all mods and that doesn't fix it. The only mod I can imagine having any effect would be the unofficial patch (other mods are texture replacers, ui/map mods and monster replacers). All I can think is that the unofficial patch killed the script on the empty vial, if such a thing is even possible or makes any sense I was able to use the phial once, and that was it.