Some of the Mac computers are not reflected in Mac Warranty Status report in SCCM.
Parallels Mac Management for SCCM requests information from https://selfsolve.apple.com/.
When such requests are sent frequently from any host, then Apple site stops responding for some period of time (approximately 2-4 weeks).
The request is sent each time Hardware Inventory scan happens.
Our Development Team is aware of the issue and working on a resolution.
Schedule Hardware Inventory scan for one time in two weeks: