.gp files

Hi there, I've been trying to import a .gp file in the latest version of muscscore. The piano score comes through just fine, but the tab has shifted around a lot (i.e. same notes on different strings etc.). Makes it a very different piece to play! Any suggestions on how to import the original tab unscathed? I'd like to be able to make some amendments to it but not to have to rewrite it bar by bar!