I was quite desperate :-(
Was running iGO Primo on Samsung S3 Android 4.3 stock and I was able to see and use skins. Installed on the same device CM13 ROM / Marshmallow 6.0.1 with the same iGO configuration, and NO SKIN is detected! No matter which skin I download and place in the Content/skin folder, they are not visible in the settings > display window in iGO :-(
I have tried to add my resolution to the info.ini file with no change. The resolution should be the same running with a 4.3 ROM and 6.0.1 ROM. Is there anything else I can try?
For some reason the resolution was treated differently on the two android versions. When adding the correct resolution as added to the About screen by the Resolution.zip utility (THANKS A MILLION!!!) I was able to use the skin. This was not needed on 4.3 and I was able to use it without having my resolution listed.