Hey, I'm seeing a similar issue (thought I'm not so early in the game).
I skipped the second Adventure (the one that starts with Attack on Sandpoint, can't remember the name) with Valeros when I initially played, so he's missing rewards from there. I decided to go back later and get them, but I'm completing scenarios and not getting rewards.
If I go and look at completion, it looks weird. There are locks on all adventures but that one and it shows that none of my characters have completed it (though they obviously have since I am on like, 4-2 overall with those characters).
Is something buggy with the completion stuff?