I understand - I’ve been using bootcamp a few years now, but only this week updated it to win 10 and installed UE Studio and had the same issue when using parallels.
@ADemetriades
If you restart your mac and hold down the option button whilst bootup, you can then select the windows partition to boot into. As explained earlier in the thread - you will now be booting into the native windows environment, not a virtual machine, which means your computer utilises the physical graphics card, not the VM one created by parallels.
Try running UE 4.19 now, and it should run fine. I have just tried this and it worked for me and I have exactly the same setup as you.