Are they MR33's? We had this issue when we added some MR33's, you have to use the latest beta to resolve it. Certainly, at the time (a few weeks ago) the current stable didn't actually support an MR33.
geez ... what a nightmare. The latest and greatest firmware (24.12) has not solved my problem. I have 4 MR33's and all day long I get users bumped off the network with "AP has too many associations". The particular AP below has a max of 7 clients throughout the day. I'm rebooting the AP constantly in an effort to keep these people working (sales environment). I'm very unpopular this week. I'll keep looking for a solution but was hoping Cisco would come out with something soon ... it used to work beautifully.
Epic fail with having different model AP's in the same network, but some models need to run on Beta and others on production, but when you upgrade firmware, you have to apply it to every AP in the network
So the only answer is to create another network, replicate all of the settings, client whitelists, etc, put the (MR33) AP's in that new network and apply a later firmware version to it...what a faff, c'mon Meraki sort it out
I also use the MR33. And I have the same problems.
There is no solution or they simply take over the problem or change the solution.
See this post is just that.