Hot-adding new hardware to an Active virtual machine, causes a "stun" operation (shown in the logs as such):
2019-04-18T15:56:50.970Z| vmx| I125: Migrate: VM starting stun, waiting 100 seconds for go/no-go message.
2019-04-18T15:56:50.977Z| vcpu-0| I125: Migrate: VM successfully stunned.
This message is normally tolerated by the majority of virtual machine configurations, but Microsoft Clusters are highly latency sensitive, and this sort of operation violates the latency constraints of that configuration.
Hot-adding hardware to MSCS is not supported. This is expected Behavior.