People can get a translucent diffuse surface view or greyish material surfaces showing up in for their imported props or avatar models or CLO3D re-imported projects that render fine in other software's. So there are a few things you can do to over come this if this issue occurs.

Yes you can use .png image format (you may not need the alpha channel),

Downgrade your .png RGBA image to .png 8 bit RGB

1. First check that the .png image bit size if in the RGBA format , save it as RGB 8 bit > then export the image and assign to the project so on import to CLO3D the texture giving you a problem has dropped the alpha channel. This is often compared to swapping out a .png texture image from RGBA to jpeg RGB > so if you want to stick with .png the simple fix is to use an RGB format with no alpha channel. Most image or texture editing software has a batch export preset you can choose to change this .png format type from RGBA > to RGB 8bit.

If you find you have a shader material using .png with RGBA, and you need the alpha channel for transparency in your material, yet it renders poorly check 3 items in your previous CG software or image editing software:

1.  that the exported .png is 8 bit

2. that the base shader material is white and not some other color (this can cause the view of the model in the CLO3D preview window to appear greyish or washed out)

3. that the RGBA  .png texture does not have the alpha channel values for black and white flipped or sat within some mid grey value. This can cause the object to render translucent in vray and in the 3D window preview mode appear ghostly or hidden as a material surface.

4. when assigning a separate translucency mask in a fabric (material) shader using an RGB image that it is set to the correct values for black and white or grey, and that they are not inverted from a previous material shader that did not correctly invert the alpha channel on export. Not all shaders for materials in different softwares export correctly so check off this item.

So when using .png some checks and balances before you import these images can save some confusion when they next render in CLO3D.