Are they payware? Seems to me that some creators are protecting their payware content by locking it, or making it difficult to reskin. If you buy official payware content, most of it will be locked, preventing editing/cloning/committing. They probably don't want reskins of their locomotives. I bought the Nickel Plate steam set that just came out and was disappointed that editing/committing is disabled, I can clone the items, but can't recommit them. I wanted to change the whistle/bell sound, but you can't recommit the loco, even though you are able to access the files and edit the config and save it.