Hey! A new version of the Launcher was released, which I added in some extra logs which I hope will help debug your issue.
Please could you grab the latest msi from unrealengine.com and install it. Then make sure you are running with no commandline, and upload a new log and dmp for this new version.
You should be able to see at the beginning of a newer log the reported API version like <\br> LogInit: API Version: 2350904