what about the filter screen under the reservoir, have you tried cleaning it? also are you bleeding with front end off the ground? have you looked into reservoir afterward, looking for bubbles?

I haven't cleaned the filter in the reservoir. I'll try that. I've had tiny bubbles in the reservoir while bleeding. I would have expected more or larger bubbles and have only needed to refill the reservoir once, right after start-up, prior to bleeding.

What rok said. The beat way to bleed a steering system especially on these trucks is with the front off the ground. Do not start the engine until you are getting no more bubbles in the reservoir while working the wheel lock to lock.

Are you saying to bleed it with the engine off?