The suspend and resume feature is useful to save the current state of a virtual machine and continue work later from the same state, even if you quit Fusion in the interim.
Fusion does not support suspending and resuming in Boot Camp virtual machines. Suspending and resuming rely on being able to save a known state that will not change. You can boot natively into Windows in the Boot Camp partition. When you do so, the known state is lost and data loss occurs.