Aha! I *think* I have figured out what's going on, and will post the fix here for everyone:

1) My keybinds were bad - I had F1-F12 bound to various things, backspace as well, etc. So I reset them all to the default. This didn't fix anything, but now I don't have to worry.

2) I was using different client folders because my old way of doing it wouldn't let me do virtual configs. I think when I installed IS/ISBoxer it only installed in my main folder, not the slave folder. Oops I set up virtual WTFs and they all are based on the master install now. Dumb Kate is dumb - I didn't realize that it put anything into the wow folder so it never occurred to me to make sure it was installed on all clients.

I only had a minute or two to test it out, BUT it seems to work at least for switching and having follow. I don't know if it will target & assist automatically as I didn't have a chance to get in combat, but at least everyone follows properly!

Thanks for the help