Adventurer squadron bug: one specific member (slot) can't ever get bonuses

[Nohar]

Hello,
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Time: Any
Frequency: Any

World name: Ragnarok

Character name: Nohar Shiro
Retainer name: None
NPC name: "Sergent des Tempêtes" (Adventurer Squadron's main NPC)
Monster name: None
Class/Level: All different levels of classes/jobs
Party or solo: N/A
In-game time: Any
Area and coordinates: Maelstrom squadron's barracks
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Steps:
1. When talking to the "Sergent des tempêtes" (Squadron sergeant, NPC needed to monitor the adventurer squadrons), I noticed that one of my Adventurer never gets any bonuses, despite the random bonuses showing that he should get one since he would fill the class or race requirement.
2. I tried to remove said Adventurer to replace him with another from a different race and job (actual Adventurer's name: "Mujen Polajen", Lalafel M, Rogue), but the new adventurer is subject to the same bug.
3. I tried to change the adventurer's class, but he still can't get any bonuses.
4. Sending the Squad member on a mission and getting him back don't unlock bonuses, despite the fact he should be getting one.
5. I think that this specific "Adventurer slot" is bugged and that no Adventurer can get any bonuses from that slot.

Note: I changed my Great Company's allegiance from "The Order of the Twin Adder" to "The Maelstrom", but the bug remains.

You can find an image of the bug --> here.<--
In this screenshot, "Mujen Polajen", a Rogue adventurer, can't get any bonuses, despite "Rogue" (Surineur in french) being the class which should get bonuses.
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PC Specs:

SYSTEM_OS Microsoft Windows 7　Family Premium　64bit　(build 7601)

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EDITION: I may not have understand how "Affinity" and "Random bonus" work, and that specific member just never unlocked any affinity. I will make more tests. You may move the topic into the "Not-a-bug" section if I happen to be completely mistaken. Thank you for your patience.