Some help/input

Even using pressure bleeders I have seen some oddball instances where a little bubble gets passed by. My favorite go-to is cracking the lines at the m/c. I may be wrong but it’s a quick thing to try. I don’t suspect the wheel cylinders at all. If you’re not losing fluid it has to be the m/c or air in line.
So you just crack the bleeder and see if any air comes out?