I tried that, and it actually activates the pause functionality as if the print had been printing when I pressed the button. It lowers the platform and goes into the "draining pipe" routine. Then, if I hit "Play," it raises the platform again, but stops -- because I guess it's still sitting on the pause command issued in the gcode. I just tried this with the M1 suggestion you gave and had the same result as M0; it homes, then sits, but the firmware clearly has not gotten the Pause message, it's all gcode driven.

So, I'm trying two new things now: first, I downloaded the latest copy of Flashprint and I'm going to update the firmware on my machine. Second, I'm going to see if it makes a difference to print via USB instead of with SD card. I noticed that some of the gcode references I've seen state that you should use different codes for SD versus other printing, so maybe I'll get lucky and stumble on the right combination...