Greetings!

 It looks like Ivar is helping you with your situation.

However.

Someone else, also mentioned that the hero's skills were not 'sticking'.

I do not know how it was resolved.Nor, if its a problem with the game mechanics, or understanding how sets work.

Sets are useful if you know how to use them,need to change skills quickly,do so often, and have the means to operate them, i.e. the cost of setting them up,and implementing them. 

However you can change hero gear without sets, though it will still cost to reset skills.