I keep getting the message that 6/21/2017 or any valid date format is invalid from Workflow when using date functions. For example I am trying to run the function NETWORKDAYS from the Token Calculator activity and it says that 6/20/2017 is an invalid date format. What format is it looking for? That is a perfectly valid date format and that is the date format that workflow uses whenever I ask it for a date.

Here is the full error message

    6/20/2017 3:36:16 PM    Calculate dates between start and import     Invalid Date Value:  Function: NETWORKDAYS Expression: NETWORKDAYS(%(Start Date) ,%(Import Date) ) Message: 6/20/2017