Symptoms
You have a virtual host with VMs, and licenses for Virtual Host workload (such license can be used to back up 1 Hypervisor Host Server and up to an unlimited number of virtual machines that are residing on the Hypervisor Host Server).
When you check the details of host and VMs with applied plans, license assignment is correct.
However, if you look under Settings -> License usage, one or more of Virtual Host licenses are assigned to VMs without Agent, or the licenses are shown as "not assigned".