Valkyrie / Rage not getting experience

[Avi]

I know this question has been asked before but I recently started an easy game and it's not letting me level the rage abilities.
So far I've collected 3 valkyries, almost cleared the 4 starter islands and yet my rage - experience doesn't built up.
I've not had a new ability screen pop up for different rages. Am I missing something? Did I forget to talk to someone?

To double check I've loaded an old game (back from 2012) and there the rage does get experience points (game on normal settings).
Is this a new bug? Am I overlooking something obvious that I did not in the first game? Is rage-experience "disabled" in the easy mode?

I was hoping for a clear answer other than "you need to collect a valkyrie first" since I already have 3 of those.

Thanks in advance for any clarifications.