So, Ronster, what is the exact model of your Samsung HDR 4k tv? You linked to a MU6100 calibration page on pg. 3.
Is MU6100 the model listed on the back of your TV?
Grayed out calibration options with different sources is not a feature, that sounds like a bug to me.
The MU6100 has a firmware update as recent as this month:
https://www.samsung.com/us/support/owners/product/2017-uhd-smart-tv-mu6100
Are you up to date on that?