The original intention and function of the external psf maps was that they could have a different shape/wcs from the image maps. Recently (not sure exactly when) this has broken and now the priorized fitting breaks if the input image and psf map shape/wcs are different.
Additionally, if the psf map has some areas with nan for any of the a/b/pa values, then regular source finding and/or priorized source finding can fail.
The original intention and function of the external psf maps was that they could have a different shape/wcs from the image maps. Recently (not sure exactly when) this has broken and now the priorized fitting breaks if the input image and psf map shape/wcs are different.