Somehow I cannot find where it’s specified exactly (like some other things too 
) It undirectly follows from: https://help.author.envato.com/hc/en-us/articles/360000471803-AudioJungle-General-File-Preparation-Guidelines “You may choose, to upload the main track, a shorter loop version, an instrumental version and a logo version” and https://help.author.envato.com/hc/en-us/articles/360000471543-Logos-Idents-Upload-Instructions “Please also note that Logo Packs can only contain Logo audio files. You cannot mix-and-match audio Logos and files you already have in the Music category.”
I remember someone quoted the reviewer’s answer on this point on forums, Cannot find it so far but I’m sure such requirement is existing.
I agree it’s not a perfect rule for many reasons. But not we who are to set the rules and to place it findable easily. 