Similar conflict with using Page Links as well, where the select styling disappears and cannot be seen onscreen.
Found the conflict is with Toolset Types. This is a widely used plugin, and suspect it’s due to their “front-end display” feature.
Hope this helps someone else looking, and also hope for a fix.
Yes, the posts were being edited on the backend only. Upon a publish/update, the information was retained from the previous save and would not update (back or frontend.)