You likely won't see "problems" as in "not working", but you might see weird performance issues. For example, the Win10 implementation of the mixed-core driver is pretty naïve, and will simply assign any thread with priority lower than "Normal" to an E-core, and "Normal" and higher get P-cores.
This means that any process that tries to say "hey, I don't want to disturb you if you are doing something serious" and lowers its thread priority will never be able to take advantage of the power of the P-cores, even if there are P-cores doing nothing. I do this all the time when I am encoding video, and set the priority lower. Without mixed cores, this allows me to keep using the computer without really noticing that the encoding is going on, and when I walk away, the encoding ramps up the speed to take over most of the machine. With mixed cores, I still wouldn't have any issue using the machine while it was encoding, but it would never ramp up.
Plus, I don't know what kind of cores Hyper-V exposes to the VM. If it is a generic core, then the OS scheduler on the VM won't be able to do any adjusting itself, and Hyper-V would have to assign VM threads to appropriate cores. OTOH, if Hyper-V doesn't distinguish between the two core types when assigning a core to VM in a "runnable" state, then some VMs would get only E-cores, and some would get P-cores.