Using New Outlook on Windows for professional communication and productivity
The fact that you have created duplicates was acknowledged as a downside by the original poster of that export/import method. However, by NOT *contacting Microsoft Customer support* earlier, escalating if need be to someone who knows what they are doing, you have probably now corrupted the MS server copy. It's a live *backup mirror* of your contacts, so if you corrupt the local copy, the server copy reflects that.
Microsoft alone has access and control over the server copy--and there is *always* a server copy. As I've also outlined, you do NOT have to wait on the phone for assistance. You simply place a request to have them *call you back*.
Microsoft has moved to an all-online Outlook, similar to Online Hotmail a few years ago. There is no longer support for a (promised) Desktop version of mail. In fact, they've been keeping server copies of our Contacts for many years now.
Please, folks, follow the steps I have repeatedly outlined, which merely check if your contacts exist somewhere and set options to view them. Then, if still required, contact Microsoft Customer Support and have them call you back.
Please, do NOT hack around with local copies or you risk corrupting the mirror copy on their servers.