Are you setting the rotation at the web map level or at the service level? Symbol rotation is not fully supported in our app today.
I'm hoping for a positive update to this post as I have the same need. I need to display photo points and wildlife camera locations with rotation in Collector. Rotation symbology was set in the web map and displays properly. In Collector (not offline) all of the symbols are orientated north regardless of azimuth (rotation field). Is rotation supported in Collector nearly 3 years later?