Server/Client: 8.5.5:

I am trying to implement the built in DaysBetween variable. But it only seems to work when tested interactively. At runtime it seems that all DATE variables with date input resolves to 0.

I have put a couple in a write file task to test it, and they return expected result in the variable tool but not at run time:
{DATE(DaysBetween|2019-12-04|2019-11-04)}
{DATE(WorkdaysBetween|2019-11-01|2019-11-04)}

Am I missing something?

In the example the dates passed in are in a different format then what you show. Could that be it?
Variable tool when I select the days between function:
{DATE(DaysBetween|11/4/2019|12/4/2019)}
30

when I paste your example in I get 0.

I'm in the U.S., maybe it's related to the default date format for the machine?

Ahr, of course!

Thank you Gary_W for clarifying that. For some reason our server host user uses the despicable US notation...

I will put a change request for input masks.