Thunderchild comes with a BSA file that causes conflicts with SkyUI.  This is documented in many places, including LOOT.  While there are steps a person can take to modify the BSA file, I felt it necessary to provided the already modified BSA for those who are not tech or coding savvy. 

Instructions

After installing the Thunderchild Mod, download this package, and extract them to your Skyrim Data folder, (usually "steamapps\common\Skyrim Special Edition\Data" allowing it to overwrite any files it needs.  The Redeploy your mods in Vortex or Resort them in LOOT.

All Credit for this mod goes to Enai Siaion  for this masterful Mod.  I simply modified one of the BSAs to make it compatible with SkyUI

if using MO2, just open this zip and drag it into the tunderchild folder in your mods directory and overwrite.

Or just make sure that it is loaded AFTER Thunderchild in your Load Order

Why?

Thunderchild comes packed with some changes to a very specific version of SkyUI.  That means that whenever SkyUI is updated, Thunderchild will just overwrite these changes.  This can lead to some conflicts between the Official Version of SkyUI, and the changes that Thunderchild makes.

The usual solution is to unpack the BSA, remove the SkyUI references, then repack the BSA.  This can be a pretty involved and overwhelming process for those that aren't familiar or comfortable with coding techniques, even if there are several tutorials on how to do this.

This mod just removes those extra steps, and already provides the repacked BSA with the SkyUI references already removed.

While Thunderchild and SkyUI haven't been updated in several years by their mod authors, this will at least help prevent conflicts if they were to be updated.