I think the whole questline doen't work as intended. For me the owlbear cub did never appear.
Prequisits are that you let it live after the encounter in the owlbear cave. From there on I've tried everything (I guess) after reencauntering the cub in the gobbo camp.
To name a few:
-refused to partake in chicken chase
-partake in chicken chase and won
-partake in chicken chase and lost
-partake in chicken chase but convinvd the owlbear cub to attack the Gobbo
then used Ilithid option to convince the ringleader to let the cub go with me. Cub takes scent and dissapears from the map.
then took about 10 full rests with any option but the cub didn't appear in my camp.
Later I killed the Gobbo leaders, all the gobbos in the temple, courtyard, camp, guarded entrance, blighted village, you name it. Cleared the whole map, spared none including those cruel Gobbo kids. I was about to launch a crusade to kill any gobbo in Faerun but recieved en email from the Hague to stop bloody gobbociding

Other guides I found tell, that you simply have to kill at least the gobbos in the courtyard, but if you kill the gobbo leaders before the owlbear is in your camp, you'll never see it. Somes sources also claim, that you loose the cub aber the victory celebration in the camp.
So my advice is how you should approach it :
- it doesn't matter how you handle the owlbear in the gobbo camp as long as you gain it's trust and is willing to follow you to the camp. You just need to a couple of animal handling checks
- checks are considerably easier if you have Silvanus Blessing buff from the grove and the cleric'd guidance buff active
- after you made this successfully - you get something like the owlbear would follow but is afraid of the gobbos so you have to deal with them one way or another - kill the gobbos in the courtyard but do not (!!!) kill the Gobbo leaders (!!!)
- return to camp and take several long rests to see if the cub eventually appears.
- still chances are that you lose it after celebration party