The "501005" check message from the 501 "part master data" message class has been revised. This allows user-defined layers in macros that were stored at parts to be found more easily. As a consequence significantly more check messages are now generated for user-defined layers than before the revision.
See also
Extensions in Layer Management
P501005: The layer <u> assigned to the macro <x> (<y> / <z>) is user-defined