We noticed a problem in our SharePoint 2013 document libraries. When uploading documents to a set of documents in a document library, the available content types in the root document library are available in the document set , even if this same type of content is not available for the entire set of documents. This is particularly difficult because users do not see their documents in document sets because they have been incorrectly labeled as an incorrect type of content, as is the case when users place / drop items in sets. of documents.
I would try to edit the new pop-up document to eliminate these invalid content types. Is there a way to query the properties of the document set to search for valid content types?