We are using SharePoint 2013:
In our solution we have multiple content types as child content types of "Document Set". In some cases, which we cannot reproduce, the Document Set loses its Welcome Page. i.e. when you click on the Document Set's Title to open it, only a regular "Filem List View" appears, but the Welcome Page does not.
For some reason this doesn't affect all objects of the same content type, just some. We cannot figure out how to fix this.
Would you have any idea that can help debug and fix this?