Have been using this combination for years and never had a problem with it. A few days ago it stopped writing to flash. I have never looked too deep into what happens when debugging or writing to flash but it seems the Reset line needs to go low for about 20 ms and the debug line must also go low. The debug line has activity but nothing on Reset. Sometimes the reset stays high and other times it stays low. I'm finishing a big project! I had two projects open when all went bad. I believe I had two projects open at the time.
Please excuse the post. Just before slitting my wrist I found there was no problem at all. Reset function going into Background Debug confusing but all is well. Problem was configuration issue with Port A Data Direction Register out of reset. .