I am currently playing on Windows 10 with the 1.3 TELP patch which came with the GoG version. I started the Initiate to Healer promotion quest, selected the character that I wanted to do the quest, and double checked that the character has the quest. I then talked to the apothecary, got the brush from the hag's cave for the lock of hair, and returned to the apothecary. He then said to wait two hours, and I ended the coversation. I check the log, and the quest is gone. I talk to the apothecary and have no prompt to pick up the potion after two hours. Not sure what to do now. Anyone else have this issue before?

Don't you need to talk to the mad guy in the cell outside the town hall? Or am I thinking about a different quest?

EDIT:
Quests bug all the time in MM9. I recommend never overwriting saves and just saving in new slots each time.

Yes I did, in fact I reloaded from a save point before I even went to Guberland, and ignored everything else in the town but the quest. First I talked to Nutty Nurtigan, then went to the quest giver to get the quest. I went to the apothecary to find out about the potion. I went to talk to the hag and then get the brush. I went back to the apothecary, gave him the brush, and he says come back in two hours. I exit the conversation, and the quest is gone. I talk to the apothecary after two hours, and no prompt for the potion. Not sure what else I can do. I had the quest up to the second conversation with the apothecary, and afterwards its just gone.

I'm not sure why it's not working, but I have a few suggestions:

1: Talk to Nutty again even if you don't have the potion
2: Try waiting until dawn before giving the apothecary the brush
3: Leave Guberland and return
4: Make sure it's one of your created characters that engages the apothecary (Make sure Forad Darre etc. isn't the active character). Also make sure no inventory is full (can't remember if this is a thing in MM9)
5: I can't remember the mechanics of the quest, but are you absolutely sure that the potion is given through dialogue? It's not sitting on the counter of appearing in a chest etc.?

None of these are particularly amazing ideas, but it's worth a shot.

Thanks for the suggestions, but it didn't seem to fix my issue. I read up on what the TELP 1.3 patch was supposed to fix, which addressed the Nutty Nurtigan quest, but in my case it is deleting the quest before it is completed, so I am unable to finish it. I have an old computer with Windows 7 on it that MM9 works fine on, it just may be an issue with incompatibility with Windows 10, although not sure. Thanks for your help.

That's a shame. I'd try to find a trainer if I were you then.