I just defeated The Beakinator twice for the daily garrison battle, and it has not given me the Mark of Pet Mastery needed for the quest “Scrappin’”. I’m at a loss for what I should do. I submitted a ticket just in case it is bugged, but does anyone here know what I should do?
Thanks!
The Mark of Pet Mastery isn’t a physical item that shows up in your bag. Try speaking to the quest giver and see if the quest completed without your noticing the ‘quest completed’ notice. Confusing, but that’s the way this one works. 
Unfortunately, I am not able to complete the quest, it still shows up as 0/1 in my quest log.
Hm, I’m not sure what else to suggest. I guess you will have to wait and see the results of your ticket. Unless someone else has any ideas?
Do you have other Characters doing Garrison fights?
If so, if they have done the fight that day, then they have earned the Mastery Mark, and it’s one per account.
Worse yet, if another Character has earned the Mark and has not turned it in, it may carry over. Not sure, but i think i did something like this.
Another scenario. If you do the pet battle first, then pick up the quest, then do the pet battle again, you will not get the quest completion. You will have to swap to another toon, pick up the quest on that toon FIRST, and then do the pet battle. The quest only gives you credit for the first daily win on a toon. This has been an issue with garrison pet battles since Draenor was current.
The quest is account wide so go to the alt and do the pet battle, quest complete.
this just happened to me today. i have no lvl3 garrison on alts. all pet content is done on main.
battled today and does the “yeah i won” animation but no mark was checked off in mission description.
ill probably just check back in witb it tommorow.
Did you ever figure this out? I’m also encountering the same issue.
I had that happen about a month ago. REloaded everything, disable everything, no joy. After 4 rounds of tickets typed out in excrutiatingly simple detail with customer service they did something on thier end and set the quest to completed and awarded me the rewards… pain