Going to hijack this thread since I have the same issue. First things first, here my system specs:
Windows 10 Pro
AMD Ryzen 7 2700 Eight-Core-Prozessor, 3200Mhz
MSI X470 Gaming Pro Corbon (MS-7B78)
4X G.Skill Tridentz LED 8GB
NVIDIA GeForce GTX 1070
So, When I build the PC it seemed to work fine even with controlling the RAM LEDs. I only used MSI's Mystic Light and as I said it worked fine. But then for some reason I can't explain, The RAM started to do his own thing. One day one of the RAM banks went dank and no matter how many times I tried to re-apply the setting (Including new installation of Mystic Light), the RAM would remain dark. I then downloaded the Gskill software to control the RAM but even though it automatically disabled Mystical lights, it would not communicate with the RAM what so ever no matter what setting I tried. So I kicked that one off again and went back to Mystic light. After a complete Windows re-install, All RAMs are now working again and I have control in MSI ML. But again, When I change the setting, it will change all LEDs at first but after a few seconds (Never the same), all the RAM LEDs go back the the same pattern which is "Rainbow" I believe.
First I thought it might be an old setting from the Gskill SW overriding the ML software so I searched the regedit but dint find any hints that it would be the case. Rally not sure what to think here simply because I had it working just fine at the very beginning and now it always switched back to the rainbow setting.
Thanks!