Yes - this is key - check your pickup wiring.When I measured on my NG3 (which I think has the same measurements as a Z3), the neck pickup was centred where a p bass pickup would be, and the middle pickup was centred the same as a Stingray.
I like middle solo if I have the pickup wired in series, but I only like Bridge/Middle in series if the middle pickup is wired in parallel. Would be nice to install a S/P switch at least for the middle pickup. In either case, I wouldn't want to lose the neck solo option.
I use the middle solo series for a modern P with a bit of aggressiveness, the solo neck series is more for a vintage smoother, round P sound (IME YMMV…)