The bug I ran into had to do with the dropdown slide selector not changing the actual slide when editing in the design panel. It showed the slide was changed but closer inspection of the element tree inspector showed the slide had not. I narrowed it down to a problem where the program needs to have a least two slides in order to assign ID's to the element. The only way to achieve the assignment was to create two slides, save the project, and then reopen it.
If this helps, this is the startup template I use to keep my sanity, as I spent hours wondering why all my changes were getting messed up when using the dropdown slide selector.