When selecting a Date field in ArcPad, the Date field is displayed as '//' after a Windows 10 device is updated with the Windows 10 Creators Update release.
This issue is acknowledged by Microsoft as a bug and is fixed in the following update:
https://support.microsoft.com/en-us/help/4022725/windows-10-update-kb4022725
For more details refer to:
https://community.esri.com/community/gis/applications/arcpad/blog/2017/05/18/windows-10-creator-update-and-arcpad