Another technique that may assist. Make sure that the two little holes in the bottom of the master cylinder are clear. Position the bars so that the master cylinder is at its highest point.
With all the slave cylinder bleeders closed, squeeze gently on the brake lever, you should see some bubbles rise out of the master cylinder bleeder holes. Allow the lever to snap back.
Repeat until you see no more bubbles or your hand gets sore.
This is what normally happens to air bubbles generated in the vertical lines in everyday use. They rise to the top and get squirted out when the brake lever is applied. The bottom bleeders are only there to release pesky bubbles trapped in the slave cylinders. And of course to allow flushing out old brake fluid with new.