The new version ios app cannot use the phase one P65+ Raw file. In addition to the iPhone, the same problem occurred after updating the app on the iPad. The files originally in the cloud can only use intelligent preview, and cannot be read after downloading the original version of the file.
Actually, according to the page you linked to, the Phase One P65+ is very old and was already supported in Lightroom Classic 3.5 (last item on the list of Phase One cameras)...