For several days customers are telling us, that flyouts suddenly close. It happens while you try to scroll by touch or you click on the flyout. This behavior has been identified as Windows 10 Issue. We don't exactly know which update is the reason. However, the Fall Creators Update (ver 1709) is solving the issue. It is distributed by Microsoft automatically. Some users didn't get it yet. By using "Search for Updates" in Windows 10 it can be installed manually.
If Windows doesn't find the update it's possible to download a little update tool from Microsoft which starts the update independent of the Windows Update.

After installing the update, T2ndB behaves as predicted.