Using the Fabric launch modpack with 1.14, it loads fine with Oracle Java 8 but with OpenJ9's Java 12 there is an incompatible class change error: https://pastebin.com/691bdpAC

The versions of Cloth-Config and ModMenu appear to differ compared to what ShulkerBoxTooltip is compiled against, but the fact it seems happy on J8 but not J12 is very strange.

This is wierd, the log says cloth config 0.2.0+build.12 but ShulkerBoxTooltip includes the 0.2.1.14 version of this mod...

You are using the pre release 4 version of the mod, could you try with the lastest version to see if it is working, I changed how the mod menu compat is handled in this commit, so this might have already solved the issue

Confirmed fixed in the latest version 1.1.2 (I'm on Java 11). The launch pack will need to update.