Im developing a custom solution for one of our customers using the Client Side Object Model. One of the requirements is to add a content type using CSOM with document as its parenttype. This is successful however when I create a new document in the document library based on my content type X, the content type switches to its parent"Document" content type instead of my newly created content type X. I would expect that the document is saved under content type X.

I also noticed that the properties of content type X are not loaded in Word/PowerPoint/ these are the same properties as the parent Document content type.

The templates that i use are stored in another document library with the same content types.

Hi,

Have you changed the default content type to your content type.  By default it takes the out of box content type such as Document.

You can change the order of content type by going to the Library settings "Change new button order and default content type" as shown in the screen shot.