Problem Implementing high side P channel mosfet power source selector
Interesting problem!
As you have already determined, your circuit relies on the Q13 and Q7 turning completely off.  However, you are stable in a state where there is a low current flowing through Q8, Q10, Q12, and Q14 sufficient to provide 0.8 volts on R36.
One way to solve this problem would be to make the connection at input 2 in such a way that it disconnects the connection between Q14 and R20 whenever you disconnect input 2.  Then, point A will be pulled to ground and all will be well.
Good luck!



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