Captain Crimson set grants no additional mitigation from the RCR added by the Barbarian skills Relentless or Sword & Board, despite the fact that these are shown on your character sheet.
Additional details, including video, are here:
It would be great to at least hear whether or not this was intentional.
What’s being discussed is not the RCR itself. It’s mitigation from the CC set coming from different RCR sources.
And in some cases, stuff that provides additional sheet RCR (such as the Barb skills Relentless and Sword & Board) does not provide additional mitigation.
Did you watch my video from December of last year? At that time, it was not working.
For instance, now, when you hit the trigger point for Relentless with CC, your toughness is basically quadrupled. (2x RCR + 1/2 damage). But back then, your toughness was only doubled (just 1/2 damage. 2x RCR had no effect on toughness).