Sorry you are frustrated here, but we are indeed crossing each other in communication
1 - The 2 issues - One was an issue with communication between 2 items on your site (redis in this case) and the other is related to change in data on your site. I completely understand you feeling they are related, but its like saying because it was raining at the same time your data changed, it was caused by the rain.
2 - The question on the group, you are misunderstanding entirely. Im not asking what moved them out of the group you believe they should have been in. Im asking what put them in the group they should have been in firstly. Im asking this, as if this was by something that was automated, such as a purchase, a promotion, or something similar, it could be something wrong in that process that has caused it to revert.