Okay...if the clients are losing their ability to associate to the APs after making this simple change, then there's some sort of problem here that I don't understand. (bug?)
I'd recommend reaching out to GTAC in this case to discuss the issue.
If you want to try this again though, as I mentioned earlier, look at the Event History section on the controller to see what the APs are doing while the clients are attempting to connect. If the associations are actually being rejected, the logs shown there should shed light on WHY the rejections are occurring.