Go to switch test and see which optos are actually not registering. You checked the column wire but didn’t mention checking the row wires.

So, for example, if you have a loose wire on the trough eject row it’s going to cause that problem.

You also mentioned that swapping the driver board worked for a little bit. That could just be because you disturbed the wires enough to get continuity temporarily. Same thing with your column wire continuity test. You could have an intermittent (loose solder joint) connection on that column wire that passed at that moment and fails as soon as the machine vibrates during play

ID the intermittent/failed opto and get under the playfield and physically inspect every switch connection on that opto’s row and column