Welcome to the Forum.
It is really an interesting phenomenon as Pioneer's laser calibration is one of the best (much better than of JVC, btw).
Please, provide the following information if possible:
1. Burner type, firmware version.
2. Media Code of the disc that does not play in the Pioneer.
3. Make a try to burn with
CloneDVD2 at the certified speed of medium used, that is set the burning speed in the software (not the "maximum").