This has happened 7 times now to me in the last week and a half where starting a keystone causes my Cinch of Unity to sometimes go into a state where it does not work whatsoever until I re-equip the belt (which is not possible during a keystone).
I reported it here 5 days ago but got no response, however, this issue continues to occur and cost me the M+ run when it happens (10-15% of my keys!) because now suddenly I go to press a major CD during tough moments and it just flat out doesnt spawn my celestial like it says in the tooltip.