Little problem with materials and textures

Development Rendering
1

hi everyone,
I’m new in the forum, my name is Paolo
I’m looking for help for a problem, I attach gif
why this happens?

thanks

Paolo MatEtex.gif

2

Open the material. It’s likely that something has changed in an external file(texture) that broke the materials it was used in, so you should see a warning.

3

Either the editor is not able to find the textures that material is using (.uasset). It might have been moved to another directory by mistake i guess. Sometimes its streaming issue. So you can try to clear dump or simple restart might also help.