Here, format should be R (which is RGBA)
The texture was loaded with a format of TEXTUREFORMAT_R.
The texture load itself only loads the red channel. However, the property for texture.textureFormat has a value of -1.
In the callback of _createTextureBase, when the texture data is uploaded to the GPU, it is using the correct format value.
it looks like the format of the InternalTexture is not being initialized, so it keeps defaulting to -1.