Can anyone tell me how to enable displaying inline attachments in Exchange 2013/Outlook 2013?  

I have tried adding 

<add key="TreatInlineDispositionAsAttachment" value="true" />

to the EdgeTransport.exe.config and restarting Transport service, but nothing changed.

This attachment does not appear within Outlook or OWA.  It does appear via Active Sync or if I forward to my external Google Email.  The file is an image.  This is not an email signature

Found this: https://msdn.microsoft.com/en-us/library/office/dn726693%28v=exchg.150%29.aspx?f=255&MSPPError=-2147217396#sectionSection2

which leads to this: https://msdn.microsoft.com/en-us/library/office/dn726694%28v=exchg.150%29.aspx?f=255&MSPPError=-2147217396

Not sure if it will help or not, but it does specifically talk about inline attachments in Exchange.  Good luck.

This is only for EWS.  This would not apply to outlook/OWA.