I always just have the default eq target ring regardless of what UI I load.
The default eq target ring is just a single color texture
I've tried 5 different ones from the 3d target ring downloads as well as entire UI's all of which are updated in 2022 or newer
1 - delete eqclient.ini (incase I had something disabling it)
2 - Place targetindicator.ini + images from download into .\uifiles\testring
3 - Load game, make sure "Show 3D Target Ring" is checked in Options>Display
4 - Load UI via /load testring or via the Options menu