Apple keeps changing how their program works, and when other applications have dependencies that get broken, those other applications won't operate as intended. Pioneer is working to address the issue, but these unforeseen changes sometimes take a while to be corrected. In the meantime, you could try downgrading your iTunes installation to 12.1.x.
Pioneer would like to thank you for your patience during this time and we will announce any information or updates as soon as it's available.
It is my professional opinion that working DJs should never adopt the latest ANYTHING until it has been proven that there are no conflicts or problems with everything else you need/use to do your job as a DJ.