What kind of diodes did you use?
Schottky will work best, with a lower forward voltage drop.

You can also lower the value of the pull-ups.
Drop to 1K if you have to.

The INT input on RB0 is a Schmidt trigger, so it has to go above 4V to trigger a "Rising edge", or below 1V to trigger a "Falling edge".
It must see a rising edge, before it will recognize a falling edge.
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