I am someone else who has this exact same issue, but I have done some extensive troubleshooting. I want to share with everyone what I found since I have read countless threads and posts and CORSAIR has shown very little concern about this, which is highly disconcerting since this fans are not cheap.
I have:
H150i Pro
6 LL 120mm RGB Fans
4 LED Strips
1 Lighting Node Pro
1 RGB Fan LED hub
All 6 fans are connected to the RGB Fan LED Hub which then connected to the Lighting Node Pro and the 4 LED Strips are connected Directly to the Lighting Node Pro.
I had 5 out of 6 fans start flickering constantly on my if I have any kind of pattern going. If i selected a static color, say red, 2 of the 5 were half red half purple. The other three were a blue-ish purple. I tried all the suggestions about using older software and firmware. Even trying to go back to the old Corsair LINK software the fans still had the same issue. I finally decided to play around with the order in which the fans were plugged into the fan hub. Long story short, I was able to get 5 out of the 6 fans working just fine. it appears that the cause is a bad fan. ended up is the bad fan in the #6 port. If I plugged it in anywhere else in the line, it would cause 4 of the other fans to flicker as well. Putting it back at the end made everything work fine except for the one fan.
I can't verify it is truly because of a bad fan issue, because I don't have any spare LL120's laying around, but it seems fairly likely that this is the cause of at least my issue.
I will try and RMA the fan with Corsair and update this post with the results when I have them.
Hope this helps someone, because if you are anything like me, this issue and lack of any kind of solution from Corairs on it is driving you F-ing crazy.
Update:
This is indeed a fan problem. Not a firmware, Lighting Node Pro, or anything else people are guessing at online problem. Follow what I did above to help you troubleshoot your problem. If you think you know which fan is the culprit, place it in the 6th port and then all others should work fine with the exception of the bad fan. Then contact Corsair and RMA it.
Good Luck,
Steel Reign