When you export your reference list to MEDLINE format, only the journal references are included. References to books, conferences, or other materials (as well as references that did not successfully parse) are not included in the exported file. MEDLINE format is designed primarily to reference journals in the PubMed database. 

RIS format requires fielded (i.e., parsed, or fully structured) references, where each reference is completely broken down into its component pieces (e.g., author name/s, year, title, source). The references that appear in gray font in your Edifix output have not been parsed, and so do not contain enough information for Edifix to export them to RIS.