I have installed WAB DE 2.7. I have had WAB DE 2.2 and 2.4 up and running for quite some time no problems.
But, when I install 2.7, it gets to "Repository Items Refreshed" and then the app fails to go any further.
It started with no problems right after install. But, after I closed it, and re-opened, it does the refresh thing.
Refer to the screenshot for what I am seeing: