Hello,
are you using 11 different materials? The material manager inside Corona Proxy should create layers for each material that is used on an object, with additional layers if one material is used with different mappings. If you have 1 Material assigned to 2 poly selections, layers for these two tags will get collapsed into one. (We are still thinking of improving this workflow)
If you are certain that you are using 11 different materials and only 10 layers show up, would it be possible to share the scene with us so that we can improve on it?
Thanks,
Jan