03-27-2015, 01:20 PM
It's probable that setting Preview mode to Delayed or Manual the "problem" goes on. Considering you were cleaning the field, the computation behind the dialog was failing.
If Preview mode is Auto, for every character you add or delete to a field or even if you clear it will be fired a call to the "update" process. In that case, the formula would be not valid.
If Preview mode is Auto, for every character you add or delete to a field or even if you clear it will be fired a call to the "update" process. In that case, the formula would be not valid.