@olivierlambert - With the host not able to evacuate, i will have to manually move VMs around to other hosts in the pool and then perform maintenance on the host. Imagine you have to do this for few hundred VMs and multiple physical hosts.
Also, the issue is not just the evacuate, if the pool ha is enabled and you disable all the ha property for all VMs, it allows to put the host in maint fine. But when i tried to disable the maint mode, i got this:
"code": "HA_OPERATION_WOULD_BREAK_FAILOVER_PLAN"
So, i disabled ha on the pool, then the disable maint on the host worked fine.
I think whole HA needs to be fully validated and every aspect needs to cross checked, otherwise i dont think its production ready.
For smaller environments, it might not be too much of a pain but even a medium environment this needs to be fixed.