Follow this tropic here, I Can't play the VC:MP because Windows Defender blocked the VC:MP's masterlist
My Spec:
Windows 10 Build 16299
I don't know but, i think you might open the browser as administrator.
It might be the router security level too.
Windows Defender is not block the VC-MP's Masterlist because ESET Smart Security is block the VC-MP's masterlist, Main Clear Closed on Request.