This is definitely a weird issue.

Anything at the connections to the LED OCD, input or output, would affect the other lamps in the same row or column.
It happens with multiple LED OCD, so it can't be a one off "oops, lamp #68 is set to 0%" or something like that.
We have seen other FT games with working LED OCD.
Without the LED OCD in this game, #68 works.
Bryan can correct me if I'm wrong, but this LED OCD in a different game, #68 works, right?

One note is that I originally thought you were talking about the Caster's Club lamp that is on the plastic. If it's just a regular insert, it's even more mind-boggling.

If I had hands on, I would start by using the software to have the LED OCD directly drive the lamp. That way, you know it's not the input to the LED OCD causing the issue. Assuming it still doesn't light, I would put a lamp and diode in parallel with the non-working lamp using test leads. You can do this either at the LED OCD outputs or at the lamp. At the lamp, you are also testing the playfield wiring, obviously.

Yellow column 6 wire --- diode ->|- --- lamp --- Red row 8 wire

My favorite matrix test tool is the Siegecraft tester board, and if this was attached instead of the playfield wiring, it would be easy to see if the game's outputs are being interpreted properly and if the LED OCD is driving the lamp.

The main difference is that the output from the LED OCD is a higher frequency PWM signal. Maybe there is something different about the diode or socket in the game.