Rumble coin quest line - Bugged?

Hey Blizzard and WoW players.

I just started playing again since I left in 2006 and incredibly I think I encountered a bugged quest line that frankly shocked me a little bit and also made me a little pissed because it involves collectables. The Rumble Coin quest line was going smooth, I managed to get the first two in Orgrimmar but then when I handed them in it told me to return to the inn area and find the other coin (The very coin I just handed in). I couldn’t find the coin it was referring to so I went online and turns out that others are having the same issue, where they couldn’t find the other coins because it bugged out. I dropped the quest line to pick it back up but unfortunately there was no way to pick it up again.

Does anyone know if there is a fix to this that I am missing? Do I need to pay the sub fee to access my mail or something as people where saying that a coin comes in the mail? I really don’t know what to do?