SRAM 11/Ksyrium Pro/Lockring Issue

[goldmine848]

Having an issue with a relatively new setup: SRAM 11 on a Ksyrium Pro wheel. The lockring loosens repeatedly. I have tried three different rings and replaced the freehub body. It is much better than it was initially but it still needs a small turn to be completely tight after a ride. Is it possible that I need a spacer of some sort?