Hopefully someone can verify for you with a 550.
Principle is that if you put the non retainer bearing in first, then if it's too far in (it has to have a tolerance there to accommodate variation in production dimensions of wheel hub and spacers) then when you put the retainer one in, you'd then be trying to move the free bearing by tightening the retainer. That's not what the retainer is for, bearing should be positioned first and retained by the ring, only then can you set the opposite bearing into correct spacing from this.
If you don't get the retained bearing fully captured then the wheel can effectively float across the axle.