So, I'll set the stage:
I have a IIgs that I wanted to push floppies to from my MacBook. I have a db9-db25 straight through serial cable. I can connect said cable to my mac via a usb-serial adapter. It has worked previously with my IIe. I placed a SSC in the IIgs in slot 2, set the control panel to "your card" and rebooted into GS/OS. I quit GS/OS going into BASIC, typing IN#2, Control-A, 14B. I pushed ADTPro to the IIgs, IIgs responded with code on the screen scrolling. ADTPro started just fine, but I couldn't select any option as the IIgs keyboard had quit working. I also tried booting into ProDOS via a floppy and it responded the same way. Kind of out of the norm set up, but I thought it would work much the same way that the IIe did. I suppose throwing the ADB keyboard in the mix might have botched things up.