I assume you’re talking about this question:
I didn’t see it the first time (I only read certain times of day, and can’t read all questions.)
However, that question doesn’t say anything about the most basic debugging steps.
There are a number of things that can fail in your blueprints. For example, “cast to first person hud” may fail – and you would never know if it did.
I suggest you put a number of “print string” calls in the “success” and “fail” cases of each step of the way. That way you can verify where it’s stopping. Note that a final-shipping build removes the text from the screen, but it still goes to the log (assuming the “print to log” checkbox is checked in the Print String action.)
One thing that varies between editor vs shipping is what the startup map is. Maybe you’re loading a different map, and that map has a different gamemode, and that gamemode doesn’t create the same blueprint class instances, for example? If so, the “cast to class” might fail because it gets the wrong class instance. That’s one of many possible failure points; I recommend adding lots of “print string” to verify that things you think should happen, actually happen.