Six months of POLARIS progress - RX 480 ft. Crimson ReLive 16.12.1 - YouTube
I have polaris, MSI RX 480 and I have no issues with the ReLive functionality on my system as experienced by the creator of the above video. I am using same version, Radeon Software Version 16.12.1.
I actually find the recording functionality very satisfying. It doesn't work on odd games like, Half Life 1 (finally when I started playing it few days ago) but it does work on modern games like Rocket League, Quantum Break, Portal 2 and Steep (new game from Ubisoft).
In fact, I am planning to upload the steep gameplay as I recorded from ReLive soon.