For the pre-build PRS+2.0.12 beta jackie_w is correct,
this is a known bug in PRS+, which is already fixed with current state of the
repository.
You can try to build a custom installer from current repository (see
BuildingPRS+ (and get Standby-Image with the option to choose the title-page of the current book as Standby-Image, yes even with your PRS-505

) or wait for the forthcoming version 2.0.13.
HTH
Mark