[Solved] Weird transparency and shadows on object

Thanks !
After reviewing your item, I found several problems:
1- the texture has the wrong size: The map always needs to be a 256 multiple (so 256, 512, 1024, 2048...)
Yours is 2084.
2- You didn't change the normal and spec maps.
You can either create them or just replace them by blank ones (read here: sims4studio.com/thread/1079/get-eas-bump-specular-maps)

Tutorials
normal: sims4studio.com/thread/861/normal-maps-bump-editing-creating
specular: sims4studio.com/thread/1617/create-rgb-specular-objects

Let me know if this helped