TYPO3 Core

The LocalConfiguration.php has the following settings:

'SYS' => [
  'USdateFormat' => '1',
  'ddmmyy' => 'Y-m-d',
],

In all TCA inputDateTime fields in the TYPO3 Backend, you can choose with the datepicker a date and time and it displays it correctly in the US date format in the field. If you edit the date manually and leave the field, the date changed completly. Changing the date with the date picker is not a problem. This works fine.

Example: Select '07:54 10-31-2018' > Change manually to '07:54 10-30-2018' > Leave the field > Date changed to '07:54 10-06-2020'

Is is the same behaviour in Firefox and Chrome. TYPO3 running on Ubuntu.

Without the USdateFormat setting enabled, there is no problem with the date picker and manual changes.

On a Windows 10 installation (local development) the inputDateTime fields are empty after saving a selected date. USdateFormat is activated. The value is still there but not displayed.