I don't know if this is an issue... but it is still very annoying.
Let's take a simple example: I have a cap that I keep in "accessory" mode. I save it in my "content" and indicate that it is a head accessory (of course I have attached my cap to the head bone).
So far so good, however... if I look carefully at the details of my file (by clicking on info) I notice that it is considered as an ICacc (i.e. an IClone accessory).

The temporary solution I found for the moment is to save it as "Others"... and then move it to the "HEAD" category (Right Click menu): and there it is well in its place and correctly categorized by the .CCAcc extension...

I noticed this on the marketplace where most of the head accessories were marked as "Iclone Only".