I had the exact same issues as you but in my case one of the lines in the tiny board (as part of the opto itself) was broken. I soldered a small wire between the two pins and that solved it.
But since you’ve already replaced the opto units itself, this can’t be the case with your machine.
Please post your issue in the POTC thread here: https://pinside.com/pinball/forum/topic/dead-men-tell-no-talespotc-owners-club