Steps to reproduce:

• Create a 3D project
• Add two different images to your project
• Open Texture Editor and create new texture
• Right click texture and choose "Apply to selected Material"
• Drag and drop image1 from Assets to Texture - Source in Texture Editor
• Create a new state State1
• With State1 selected, drag and drop image2 from Assets to Texture - Source
• Open Material Browser
• Choose Base State and State1 in turns
• -> Material preview image updates correctly, but texture preview does not
• In Texture Editor preview seems to update correctly when changing states