Tie a guest from its own page.
The host's VMs tab is one way to link a guest. The other is the guest's own page: identity, hypervisor guest. A dead guest can still be started from here, because the click goes through the host.
Open Work › actions
Open the guest, then work › actions. Identity is open. Hypervisor guest is the host and the vmid. files01 is already tied: the host is Lab host, Proxmox, the vmid is 101, and the status reads tied to Lab host. A unique name match, when the hub finds one, is only a suggestion — press use this if you want those values, then save. Save is at the bottom of the page and writes the host and the vmid. This shot stops on the filled fields. Nothing is written again.
Linking from the host's guest list is Link a virtual machine to its host. Starting or shutting down once the link is saved is Start or shut down a linked virtual machine. The same buttons on the host, before or after the link, are Start or shut down a guest from the host.