Adamantoise Mount key item not listed

[PandyWHM]

(not a big bug, but thought I'd mention it anyway)

Platform: Windows 10
ISP: Atlantic Broadband
Type of Internet Connection: Cable
Internet Connection Speed: not sure
Date & Time: Aug 20, 2019 around noon
Frequency: persistent
Character Name: Nakti
Race: HumeF
World: Asura
Main Job: Ranger 82
Support Job: Dancer
Area and Coordinates: not location specific, but "began" in Upper Jeuno
Party or Solo: solo
NPC Name: Mapitoto (in Upper Jeuno)

Steps:
1. I traded the Admantoise Mount item to Mapitoto
2. I obtained key item: "Trainer's Whistle" (instead of "Adamantoise")
3. The key items under Mounts do not list Adamantoise.
However, selecting Abilities from the Main Menu -> Mounts *does* list Adamantoise and it works correctly. It looks like only the key item listing is incomplete.

[Dzspdref]

I had same issue. When i traded the item to Mapitoto, after the blacked-out cut scene of "installing it" onto my whistle, usually you'll see:
"Obtained key item :♪creaturename"...

and instead of getting "Obtained Key Item: ♪Adamantoise",
i had seen "Obtained Key Item: Trainer's Whistle" show in my logs; although the Adamantoise was listed in my Mounts menu.