I've run into some trouble trying to compare date fields.
I have a date value - dateNow which I calculate using the Calcuate Date control while using the "use date when action is executed" and "include time".
I then compare it to a From and a To value to see if a specific schedule applies. (these are Date & Time columns)
In my Query List action I check that the From <= dateNow <= TO.
The WF logs this:
FROM: 2015-03-06 9:00 AM
dateNow: 2015-03-06 3:48 PM
TO: 2015-03-06 3:00 PM
This means that dateNow is clearly outside of the interval (greater than TO) yet I still get this selection as part of my results.
Basically it seems as if the "visible" values didn't match the values when doing the comparison.
I ran into a similar issue in Visual Studio where the actual date value provided by SP was different than the display one. There I could resolve it with a Convert.ToDateTime and then a comparison to UtcNow. No idea how I'd go about doing that in the NWF.