Radio Button is only partially checked
Looks like an Animation Bug. When using a CompoundButton on a Fragment inside a ViewPager the drawable state is not set correctly.
This happens also for Checkboxes as seen here: Android Nougat: Why do checkboxes on Fragment have incomplete state when selected programmatically (but look fine on Lollipop).
Calling jumpDrawablesToCurrentState() just after calling RadioGroup.check(id) or Checkbox.setChecked(true) seems to fix the problem (thx @Dalmas)