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
Please see our announcement here.
Another problem with ajaxified lists and calculation positions is that the buttons (ex. delete, update record) near the elements labels (headers) are missing.
See the image:
View attachment 12108