We have one CAS and one Primary server running SCCM 1802. We have one major domain AD.XYZ.com with domain netbios name as PQR.com. There are few other smaller domains.
The domain name field for our clients and AD Groups appeared as PQR in the SCCM console. All our query based collections were set up with PQR\<AD Group name>. This setup had been running for years without issues, till last week.
Last week we observed that collections based on AD user group based were losing membership and most collection were reduced with 0 members. On investigation we found