I had a pathway error initially as well.  It turns out it is related to the GTS800 install.  Are you using the GTS800?  If so, you need to reinstall the entire -10 release from scratch (except that you don’t have to redo the individual device software updates), and uncheck the airframe load option when you do the GTS800 install.

As for the GS early arm, it auto cancels each time you change ALT.   All you need to do is the GPSS button once when you are in ALT hold mode approaching the FAF and don’t expect any more ALT step downs.  That will re-arm the GS option.