When subscribed Content Libraries are not synchronizing with the source Local Content Library, the primary troubleshooting step, as described in the official VMware documentation, is toverify network connectivitybetween the source vCenter (vCenter Server A) and the subscribing vCenters (vCenter Server B and C). The administrator must ensure that all required network ports for Content Library synchronization are open and accessible. Without proper network communication, the subscribing vCenters cannot retrieve or sync content from the published library.
Other steps, such as recreating the libraries, enabling bidirectional sync, or manually importing content, do not address the core issue of connectivity and port access, which is essential for automated synchronization to function correctly.