External Keyboard Function Keys Not Working

When using an external keyboard, certain function keys do not work at all. I've been through all of the usual suspects in settings but even though I am explicitly telling the system that I want to use the old style function keys on my MacBook Pro (2017) touch bar, they still do not work. For example F12 increases volume no matter what I do. Press FN key, do not press FN key. It does not matter. This has only started happening in the latest BETA. --> 10.14.4 (build 18E194d)