Chocobo not gaining experience

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Time: 9:19
Frequency: Always
World name: Adamantoise
Character name: Alexander Nier
Class/Level: War 62

It has been a while but I did not realize that my chocobo was not gaining experience (I'm fighting things my lvl also) It seemed to happen after using it in the stables. It has not exp gain and I don't know why.

PS4 Player

What level is your chocobo and how much experience does it have right now?
From level 10 onwards you need to use Thavnairian Onions to level your chocobo up.