This is old and marked as answered - but comes up first in Google, so just to add a comment.
Originally the poster here (the Op) was using Add Actor Local Rotation, his fix was to use Set Actor Rotation - this answered the question, but did not suggest why the former did not work. I have noticed to a bug with Add Actor Local Rotation when it reaches 90 (goes from -270 to +90), in theory it should flip to -270 at 90 so it can continue to add, but as of 4.5 it does not, it just stops adding!
Added post here: Add Actor Local Rotation Bug - Blueprint - Unreal Engine Forums