Task which is part of a larger job or smaller job, will never launch. It will stay in queue status until timeout will occur.
There are/were disconnected hosts or Virtual Center in your inventory. vRanger is trying to communicate with the wrong Virutal Center or host.
General DB cleanup is necessary.
Please Remove VC from vRanger inventory,
Remove all disconnected hosts.
Shut down vRanger, Stop all 3 vRanger services.
Start 3 vRanger services: 1 - vRanger service, 2 - FLR, 3 - API
Run the vRanger application.
Add the VC and the hosts.
Create a new job to backup the VM in question.
If you can't remove the host from the inventory please refer to KB article # SOL76690