It seems to be caused by a (file list) cache problem. Please click "Advanced" in the Drive Mapping Tool main window, then click Clear All Cache Files, and then refresh the folder.
We have improved the Drive Mapping Tool software and just published a new version today. Please visit:
https://www.drivehq.com/downloads/WebDAV_CloudDriveMappingTool.aspx
to download the new version. The new version probably has fixed the problem.
If the problem persists, please click Advanced -> Event Logs -> Send event logs to support; please also email us the detailed information about the problem. Sceenshots showing the problem will be very helpful.