I have added data validation to one of my fields. It is validated by a calculation and I have added a custom error message. Everything works as expected for Windows users but when an IWP user enters a value that would cause the validation to fail, no error message appears.

Now it seems that FileMaker won't let the IWP user commit the record if this field's validation fails but the user has no clue about the reason why.

How can I overcome this problem?

Were you able to figure this out? I am having a similar problem. I have noticed that if i use the submit button in the status bar IWP will generate an error message. However if try to submit the record using my own submit button (a script with Commit Records/Requests) then I don't get the same error message. Not sure how my submit button is different from the submit button in the status bar. Don't know if I need to create a script that will return an error message.