In version 2.5.0, an error has been detected in windows installations, which causes Dynaform data not to be saved correctly on "Date" type fields. This problem is not present in Linux server installations.
It is not necessary to run an upgrade, Windows users can perform a complete upgrade or simply replace the class.xmlform.php file at the following path: gulliver/system for the new one included in this release.
Please visit this link to download the file.
If you did not install Windows, you can download the installer that includes this patch on this link