I recently upgraded to ArcMap 10.4 from 10.3.1. I opened up a map package that was created using 10.3.1 a few months ago and all of my symbology has been changed and now references letters and symbols instead of the original symbols. The original style references are still loaded, but do not draw as they are supposed to. (Custom symbols that created in photoshop draw fine.) Has anyone else had this issue? I wanted to post here before disappearing into the weeds searching for a solution...