VMware resource sharing is NOT supported. VMware resource sharing is one of the best ways to guarantee mysterious and intermittent problems with ISE nodes. VMware configuration should be one of the first things a TAC Engineer checks for with certain symptoms because it is so insidious.
The ISE OVAs are explicitly named for their equivalent appliance model and hardware requirements:
ISE-2.1.0.474-virtual-SNS3415.ova
ISE-2.1.0.474-virtual-SNS3495.ova
While the ISE OVAs do enforce the hardware requirements for CPU, RAM and Disk, they have no way of knowing if the resourcing is dedicated or shared within VMware.