I went to Mor Dhona to do level 45 GC leves the other day. After not seeing the ! icon for Grand Company leves I found the Flame Sergeant who I figured would give me leves. His dialogue said something to the effect of "I don''t talk to anyone who isn't at least Sergeant 3rd Class.

This confused me as at the time I was Sergeant 2nd class. After shouting for a minute asking if others had the same confusion and getting nothing, I returned to Whitebrim and continued doing fates and level 40 leves.

It wasn't until I ranked up to Chief Sergeant that I was prompted that I could take on new leves. I then went back to Mor Dhona, and the ! was on screen and he gave me leves.
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Just a heads up if this was confusing anyone else.