So your issue is that your texture file is not a power of two texture, meaning it cannot integrate into our streaming system. Streaming textures require mips, and mips cannot be generated for non-power of two textures. The texture file you provided to me was 127x128 which is why you cannot uncheck the ‘Never Stream’ option.
You have two choices from here if you want it to be a streaming texture. You can use the ‘Power of Two Mode’ option within the Texture settings. This will pad you non square textures to the nearest power of two so they can be integrated into texture streaming.
Original Texture
Padded to Power of Two
Here you can see that once I have padded my texture to the nearest power of two value, it creates a line of visible pixels which I have chosen to highlight in pink so you can better understand how the padding works. You can take this route, or you can simply reimport your texture at the correct 128x128 texture resolution.
Cheers,