Formatting rule hiccup? Functionality not responding on new form when validation is

[yvette]

I have a form that has been used about 2800 times. A user just came to me today saying she experienced a problem with the form. The formatting rules suddenly didn't respond, while the corresponding validation rules did. She provided me with the following image:

What should have happend is this:

When she cancelled the form and started a new one the problem was solved.

I have never seen this problem before. What could have caused this formatting rule hiccup?

[emha]

how does the formatting rule look like?

[yvette]

Couldn't be simpler! Referencing the form control:

[emha]

ok, it's really simple and nothing what shouldn't normally work.

it that happened just once, I wouldn't bother with that. it might be some race condition - eg. some javascript include was loaded too late and something wasn't initialized correctly.

if that happens regularly then I would watch developer console for errors reported. there might be millions of reasons, hard to guess a proper one.