Can you change plugins\fabrik_element\calc\calc.php in line 94 and line 492
Php::Eval(['code' => $calc, 'vars'=>['data'=>$data, 'd'=>$data, 'formModel'=>$formModel]]);
to
Php::Eval(['code' => $calc, 'vars'=>['data'=>$data,'repeatCounter'=>$repeatCounter, 'd'=>$data, 'formModel'=>$formModel]]);