Start looking into the logs (you should see a number of errors) and start a job with AirWatch support (can always cancel if you resolve the issues).
- Service issues (Device services)
- Certificate chaining missing preventing devices from verifying the certificate
- AWCM certificate issues (this requires a reinstall if the cert is changed)
As this sounds like an iOS profile issue you should also check the certificate used under “Settings > Devices & Users > Apple > Profiles”, this would need to also be replaced with a valid certificate.
See the following for profile signing certificate impact and renewal; https://support.air-watch.com/articles/115001662348