The background for Shulker box overlay is behind the REI items screen and the items are in front which makes it hard to see the items. Can this be fixed?

I have this problem too. Have you reported this on Tweakeroo/MiniHUD also?

Yeah I reported it to Tweakeroo/MiniHUD after I figured out where to report it. They said they know the problem and will probably put in their own fix soon. I am not sure how much of the issue is REI and how much is Tweakeroo/MiniHUD.

Great! If they are aware and have a plan for solving it then I'm happy :)