Describe the solution you'd like
Show a GUI preview of what is in the shulker box (see image for what I mean)

Describe alternatives you've considered
Using modules / mods that add this to the game when hovering over a shulker in an actual container works but for some reason doesn't work with the mod.

Additional context
Either support for which or a workaround mod that adds this functionality to the game.

What mods are you using for the tooltip? Assuming you're on 1.19.4 anyway, Shulker Box Tooltip works for me:

Ahh perfect, thanks that mod works. I tried both Tweakeroo's built in preview aswell as my hacked clients shulker preview module to no avail. Shulker Tooltips works fine. Thank you!