I can’t speak for the 530 as mine is working properly.
But this is the effect of the AP NAV mode. It doesn’t do this in HDG mode. It will constantly zig-zag back, and forth along the course, probably because it is overcorrecting. Anecdotally I’ve read here that the AP in the Arrow is not very good so this may be accurate modelling. I believe @Coppersens took the AP config from another plane. the G36(?), and transplanted those settings into the Arrow.