Is this a general bug or is it just me? 

1. On the new forms Designer (V11) create a new form and add a date field and set the date format to DD/MM/YYYY.
2. And under Advanced enter a Minimum and Maximum Date Range (Notice the date format isn't DD/MM/YYYY)

Then try to submit the form and see if you get an error message like this one below where it stops you submitting the form:

So after troubleshooting I discovered that the problem is the Minimum and Maximum Date field format...

Work arounds I've found so far:

• Match the date format to the Minimum and Maximum Date values (YYYY-MM-DD).
• Or, set the Minimum and Maximum Date values to blank.