Latest firmware update trashed Access Control

I'm using a RAX120 router (for some years now) and have always used Access Control successfully.

A few weeks ago I installed the latest firmware update (V1.2.10.56) and it (or something) has really messed up Access Control.

I will see devices that are connected but blocked. I select the item and press "Allow". It goes away and when it comes back, it still shows the item as blocked. There is nothing I can do to Allow access. I see devices in that list that I know have switched to a different MAC address and so are not connected with the address that it's showing...and refresh changes nothing.

With another device I was using, every time I would "Allow" it, Access Control would simultaneously Block another device I had. (No, they didn't have anywhere close to the same MAC address.)

This all just started recently. Any suggestions? They claim they're not releasing any more firmware updates for the RAX120. I hope they'll make an exception since their last one broke it so badly.