In a setup of 4 wAP ac's administrated by CapsMan things works good for pc's and android devices, but not for iphones and macbooks. Same SSID are used for 2G and 5G. The Apple devices then chooses 2G over 5G. So I created a new SSID for 5G only. This made the Apple products to jump to the combined 2G/5G SSID (selecting a 2G radio) a few minutes after connecting to the 5G only SSID. So, the Apple devices were told to forget the 2G/5G ssid. This made them stay on the 5G network. But they does not connect to the AP with the strongest signal. They seems to connect to the AP with the lowest mac-address. If they move out of range from this AP, they rather say no network than connect to another AP. But if they disable/enable wlan when out of range from the AP with the lowest mac-address, they connect to another AP within range - the one with the lowest mac-address within range. Once they start moving around, and get within range of an AP with a lower mac-address, they jump to this AP.
So I created SSID1, SSID2, SSID3 and SSID4 and pushed them to each individual AP (5G only). Now the apple devices can manually select which AP to use by selecting the strongest SSIDx. Why cant apple devices select the strongest AP automatically? Some years ago this was a known bug in iphones. It was fixed by an update to ios. Now this problem seems to be back. This behavior is tested with 2 iphones and 2 macbook pro. All available updates are installed.

I'm guessing this is a new apple bug. Are there any settings that can be done with the APs that will be a workaround to this until apple releases a fix?

** NB. There is not enough overlapping APs in this setup to know for sure it's the lowest mac-address that is the criteria for selecting AP. There may be other factors, but for this limited testing environment, lowest mac seems to fit the behavior.

If this is very recent phenomenon then it could be a bug in iOS 12 which is fixed in 12.0.1. The bug caused iOS devices to prefer 2.4GHz over 5GHz, but it didn't affect all devices. IIRC only the latest Xs phones displayed it.

Have you ever upgraded your IOS?