Nintex Promapp is only set to work in English. This is a problem found when working with the browser in another language, Portuguese for example.
Portuguese use commas instead of dots. In timeframes, this doesn't work. If the language is set to English it works.
So when this sends to you using the comma you do not read it correctly as it is not an accepted format.
You should consider adapting the platform to all formats, in this case, comma, dots... etc, according to the browser languages.
Thank you !