I am building a task form that is associated to a request data action in my list workflow. The task form needs the user to supply a "Time out of the oven" date/time. I have tried to configure rules as below to make this happen but the form cannot be submitted in Nintex Mobile (iOS - iPad) as it reports validation errors - erroneously I believe.

My question is, what's the best way to validate a datetime control has been completed in the Mobile iOS app? Or is this a bug I should be submitting to support?

Scenario 1: Checking the value of the control using isNullOrEmpty()

I have the following rule setup and associated to my datetime control. My control is called ActualTimeOutOfOven and my validation rule is isNullOrEmpty(ActualTimeOutOfOven).

When I complete the form on the iPad as below I'm presented with the validation error bar at the top. However no particular control is showing as the erroneously completed control.

This also occurs if I change my rule to use {self} in the rule definition as well.

Scenario 2: Using {self} in validation rule