Honestly a 1 inch steak is the hardest case. There is simply not much distance between crust and centre, so a small band is close to unavoidable. Buy them thicker, 1.5 to 2 inches, and the same sear technique produces a band you cannot see.
One more variable: dry brine before bagging. Salt the breasts and leave them uncovered in the fridge for an hour or overnight, then bag. It changes how much moisture the muscle holds and the difference in a lean cut is not subtle.
Common cause of a weak seal on wet meat: moisture in the seal channel. Pat the top four inches of the bag bone dry, or freeze the brisket flat for 30 minutes before sealing so it does not weep while the machine runs. Half my early failures were this.
Middle option nobody mentions: 12 hours at 140F. Slightly pink, sliceable, and the fibres have started to give. It suits chuck well and fits in a single day if you start early. Worth trying once you have done both extremes and know which direction you want to move.
Good to know, every recipe I read had a sprig of something going in the bag.
It did. Went from a hospital looking lump to something I would order in a restaurant.