Try Ppos from GPS's
You input the Airport reference coordinates? That is usually far away in the middle of the runway, I think.
We input Ppos from GPS1 to FMS1 and GPS2 to FMS2 (GPS takes like 30 sec more than GPS1)
Try that may be it solve your problem.
It s weird that you swap CDU's and still and check WOW and nothing.
Good luck.
AM