I did a fresh install of the Windows 10 x64 Technical Preview (build #10049) and applied SKTimeStamp 64 v1.8.6 then rebooted.
I no longer see a tab for setting the timestamps when I do right-click->properties on a file as I did when I previously ran Windows 8.1 on the system.
Of course, this is just a Preview release for Win10 so it's understandable if this operating system is not supported. However, I think its worth mentioning that compatibility with this OS may need a look.
Works fine for me with the latest Win10 technical preview.
But SKTimeStamp is at version 1.3.4. If you mean StExBar, which is at version 1.8.6 then that works for me as well.