I'm using the built-in input validation feature. When an invalid input is entered and the user clicks outside the input box, sometimes that input disappears; the associated error message does not get displayed. I'd prefer the invalid input to remain in the input box. What might cause the input to sometimes disappear?

I'm using the built-in input validation feature. When an invalid input is entered and the user clicks outside the input box, sometimes that input disappears; the associated error message does not get displayed. I'd prefer the invalid input to remain in the input box. What might cause the input to sometimes disappear?