AT -my friend,the fact that the bleed switch is left in the ON position after 'bleed trip off'light doesnt's mean that you'll have bleed pressure from that engine.
So bleed trip off ---no pressure on that side of ram. (no matter what you do with the bleed switch)
Next step from QRH ---select pack affected side OFF--valve in auto will open--pressure again for the systems I've told you before.
About the bleed switch relation to the isol.valve ,hmm.
In flight ,as you say ,if by whatever reason you select bleed off-then you'll have two packs on the same source.If you add also anti-ice I bet you'll fail the other bleed also.
So,as LEM said ,annoying.
On ground,you'll have one pack operating (classic)--valve is already open.(in auto)
Selecting bleeds to off ,indeed will command a 'special'high flow on the operating pack,but has nothing to do with the valve (it's already open)