RANDOM ITEM CHESTS AREN'T WORKING [RMMV]

Seems your random variable range is from 1 to 159, have you set conditionals for each range? Is that how many random items you want?

Hmmm, I don't see anything wrong with the eventing. If you're getting the randomized items only sometimes then the only thing I can think of is that you've missed a few conditional branches. 159 conditionals is a lot to keep track of!

I don't have experience with a random conditional with that high of a range or if there's a processing delay or some such. Maybe place the wait command after the common event call? Hopefully someone else can chime in to help you.

The wait looks useless to me in this part of the code (you might want to test one frame wait before the begining of your conditions). I did something similar on RM2003 for encounters (with as much conditions, I guess) and it works fine. The only thing I could think of to lighten a little bit your code is adding a label in your event to jump at the end of the code (but it's more utility than a must, and checking your last condition doesn't have a "else" (but it only avoids to get two objects). Other than that, it could be as said ten_blue_egyptians (but testing it several times would have made it work at least once or two), an error of MV when handling message (it doesn't show, but the item/gold is still added), or your local button A cutting the event (I don't know why though).
If you're using a plugin, maybe one of them wrote over something ?

I think my general response to this would be to check the value of the variable, and see what it's value is when the chest comes up empty. You can pass the value into the debugger (not sure what that would look like for MV, though), check it with F9 (I think it's F9?) or doing a Show Message of "\v[81]".

It might be really tedious to perform this check multiple times if there is a self-switch enabling Page 2's processing. For the purposes of testing, maybe temporarily remove that line?