For running J!5.1 you must https://fabrikar.com/forums/index.php?wiki/update-from-github/ or include the new file manually https://fabrikar.com/forums/index.php?threads/joomla-5-1-and-fabrik-cannot-find-files-error.54473/post-285151 See also Announcements
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That's why I use the old date-element. Probablythe new date element will never get this possibilities !?It's kept only because of its "Advanced dates" possibilities
At that point in time I didn't even think about J5, so missed the existance of the solution