I have the same problem. I have developed several Addins for EPDM. It seems as if the debug breakpoint issues is a magic "Works sometimes" issue. When it works, I can work. When it get's fussy, I become unproductive. Seems like the problem is completely random.
Currently, Notepad launches, but no debug breakpoints flash, error, warn, nothing. Get error in Debug Add-ins window:
Could not find module implementing class.
App provides new menus, but even msgbox debugging method does not work. Unsure how to proceed. Any suggestions.