Which version of MS Word are you using? Are you using Windows or Mac (OS version)? You say you’re using Endnote X7 but did you update your software to Endnote version X7.5 (which is needed to be compatible with Word/Office 2016). Refer to the knowledge base article: http://endnote.com/kb/141439
Also, a PDF that lacks a digital object identifier (DOI) number within the file will cause Endnote to create a record having just the name of the PDF in the title field.