Can't save MAC address lists on new router

I've seen this questions elsewhere in these forums, but they were closed with no answer... I had to replace my xfinity router and the new one won't let me save MAC addresses for the 2.4 Ghz channel. I can add addresses, but when I save and the page refreshes, no addresses are saved. I have devices that only work with 2.4 Ghz, so disabling the channel isn't an option. This is obviously a software bug.