This something that I noticed the moment I got Lukot's partner card. I thought that they had fixed it after 2 maintenances, but after doing a quest with Lukot yesterday, it seems like the problem still persists. Maybe nobody has noticed it yet?
But anyways, I started a quest with the 3 Scion Class Trainers just for the sake of rising friendship and see what they give me as gift, notice how Lukot's friendship bar (or however it's called) is nowhere near to be full.
So I did the first Recommended Quest that was Volcanic Caves Exploration. After beating the Vol Dragon there was the message that said "A gift is available from Lukot"
I went to check just in case I was actually wrong but nope, she really didn't have any gifts for me yet.
I don't really know of this also happens with other NPCs, but the ones that I have invited had no problems whatsoever. Only Lukot seems so be the one with this problem, and it happens in every quest I complete with her.