DATETIME_DIFF doesn't work

I’m dealing with DATETIME_DIFF. It worked until today, but now it return “NaN”, what’s happen?

Hi @MATTEO_TONDO - the formula itself is working OK, but I suspect you have an issue in the formula configuration or in the data you are inputting to the formula. If one or both of the date fields is empty, then it will return NaN

You can get around this by testing for the presence of both dates first:

IF(AND({Date 1}, {Date 2}), DATETIME_DIFF({Date 1}, {Date 2}, 'days'))

which gives this: