Hmm. I've also tried to add the game by going to tools/import/import ROM files and followed the usual steps, selected scraping sources, the whole 9 yards and at the end, it gives me the same message, 0 ROMS imported successfully.
I may just wipe my build and start fresh. I have a few thousand titles in, but only just recently started to get serious in curating my set up. It just so happened that i wanted to start with the Master System since that console/library is near and dear to my heart. Any thing else i can try before i go ahead with a clean install?