I want to update this that we have done a full range of testing on the new Windows 10 Creators update, across all of our Epic products, and we have not encountered any issues. On all the machines we tested on, every product, including the UE4 Editor, has opened without issue.
We have also opened communications with Microsoft, but have not identified any potential culprits.
I recognize that this doesn’t help you, and I’m sorry for that, but we don’t currently have any information regarding what the issue may be that you are experiencing. We acknowledge that something seems suspicious since a few similar reports suddenly came to us for our other products like the Launcher and Paragon, however those users seem to have been able to resolve their issue. I have created a forum thread to request anyone else experiencing issues to let us know so that we can determine if there is a wider impact, but at the moment no one has responded: Potential issue loading UE4 with the new Windows 10 Creators update (build 1703) - Announcements - Unreal Engine Forums
If we have any further questions or ideas for you, we will let you know. And if you uncover anything during troubleshooting, please follow up here.
Cheers