Was the emulsion really gone, as in sloughed off, floating in the fixer? Or just no image?
You didn't mistake 68-degrees F and do the processing at 68-degrees C?
I have setup three trays with dev/stop/fix and spent 13 minutes in stop, 30 seconds in fix and no third tray.
And I have carefully measured out 1 part of developer, asked my wife what 9 times 3 was and carefully rinsed out the beaker and developed my film in 27 ounces of water.
So stuff like this will happen in the future. Sorry.