I worked through a problem this morning where I could not add a virtual machine to a pool. The virtual machine did not appear as a member of any virtual desktop pool, nor did it appear in the list of available virtual machines to add a pool. I was eventually able to have it appear in the list.
steps to reproduce:
1. configure environment with at least 2 virtual host servers in a failover cluster configuration, 1 server acting as a remote desktop services connection broker, and one virtual machine.
2. Create a virtual desktop pool on the connection broker server's remote desktop services connection manager management tool.
3. Add virtual machine to this pool. This machine should now show up in the list of machines added to the pool.
4. Migrate virtual machine to another virtual host server
Once you have completed step 4, the virtual machine will no longer show up as a member of its pool. You will be unable to add it, as it will not show up on the list of available virtual machines either. Once the virtual machine has been migrated back to its original host the machine will reappear in the list.