In Orchestrator -> Administration -> Inventory, trying to expand the VUM (vSphere Update Manager) plugin results in the loading icon spinning indefinitely.
No VUM endpoints are listed.
Orchestrator 8.18.x
One disconnected VUM endpoint can prevent all endpoints from loading in the Orchestrator Inventory UI.
This issue is fixed in VUM plugin versions "8.1.2+25062358" and higher.
This version of the plugin will display all VUM endpoints, including any in a "disconnected" or "unusable" state.
The new plugin version is tentatively planned for release in a future patch for Orchestrator 8.18.1.
A workaround for this issue when a VUM endpoints' certificate is no longer trusted by the Orchestrator VUM plugin can be found here.