What you are describing sounds as though you’re not allowing your shaders to compile. Please make sure that you wait for all shaders to compile before you try to package your project.
If you’ve created these textures on your own, please look over this documentation: [Rendering and Graphics][1]
If you’re not able to figure this out on your own, you may want to put a question in our Rendering section for additional assistance from another colleague who works with Rendering more frequently than I do.
Thanks!
Guidelines for Optimizing Rendering for Real-Time in Unreal Engine | Unreal Engine 5.1 Documentation