Check
in your file your-site\media\com_fabrik\js\form.js line 1371 should be
if (el.element && jQuery(el.element).closest('.fabrikHide').length !== 0) {
Try
in Fabrik options "Debugging" set "Burst JS" = yes
This option only forces the use of the recent Fabrik JS files.
So you had some old JS cached.
Dd you clear all Jooma and browser cache, do you have some compression stuff running which may use outdated JS files?