FragmentStatePagerAdapter doesn't call its fragments

Question

I have FragmentStatePagerAdapter in a fragment with pager. Inside pager I have two fragments to switch between them. What is happening is that when I first come to fragment everything is done correctly, but when I go back and return there again then on the base fragment is called normally onCreate, onCreateView and so on, but on fragments in pager is not called anything, getItem on adapter is not called and pager view is blank. On all fragments I have setRetainInstance(true) which is needed due to a rotation behaviour handling.

Can you help me guys what to do with that?