Hmmm... that's odd. I'm running PKHeX in Wine on my mac, and it is very likely an old(er) version of the program, as I haven't used it in a very long time. Whenever I try opening the B2 .sav I want to edit, I get the error message that reads 'Attempted to load an unsupported file type/size'. It has no issue opening my Gen VI files, however.