We fixed a database issue in Plex Media Server relating to Vbox DVR IP address changes - this may also have a bearing on multiple Vbox DVRs - suggest trying out today’s beta
Plex Media Server 1.32.6.7371
(DVR) Devices could fail to be recognized when IP addresses change (#13529)
If the problem remains, I would need fresh diagnostics - with details of the DVRs, download of the Plex Media Server, IP addresses and Vbox DVR Ids (Mac Addresses would be fine) and Server logs when the problem arises