Thank you for directing me to a similar post, will try some of the tips and tricks there! 
(Issue with out of the box Cesium Ion assets: Slanted terrain, missing textures and more)
I was using 3D Tiles For Godot v1.0.0 from the Asset library from within Godot itself.
Will switch to 4.4.1 and see if I see any improvements as well.
Cheers!