Only things I can think of:
(1) The virtual hardware dialogue for the VM will need to be closed and reopened to see a change in state. Powering down the VM with the dialogue open will not dynamically change the status of the dialogue, e.g. unfreezing greyed out controls. Sometime the main web client view can benefit from a refresh too.
(2) How much vRAM are we talking about. Is it already at the maximum for the licensed state of the host?