Apple wireless keyboard, 3rd Generation Model A1314

The keyboard generally is fine and works as expected, until it doesn't. Something happens to it where the keys being pressed are not transmitted to the iMac immediately. There is a delay of 15 to even 20 seconds and instead of sending a single keystroke if that's all that was pressed, it sends like the key was held down on repeat. Once it gets into this behavior, I have discovered no other way to correct it except removing the batteries.

I have tried shift + option and bluetooth menu to reset the bluetooth module and have even removed all devices. After a restart I got the assistant and still the problem persists. The batteries are reading full strength in the bluetooth menu and they were recently replaced.

It's quite annoying. Has anyone else seen this behavior? Any thoughts on troubleshooting/repair ideas?

It is the Apple wireless keyboard, model A1314, 3rd generation. I have the complementary mouse and trackpad (purchased at the same time) and they both work fine. They work while the keyboard is freaking out and so I am ruling out signal interference.

Please and thank you.