Now I realize that trying to access the Customize page, I got the error:
VM10743:27 Uncaught TypeError: Cannot read property ‘min’ of undefined
at eval (eval at m.template (load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,underscore,customize-base,wp-a11y,wp-util,jquery-ui-core,customize-controls,jquery-ui-widget,jquery-u&load[]=i-mouse,jquery-ui-sortable,jquery-ui-draggable,jquery-ui-droppable,backbone,wp-backbone,jquery-ui-resizable&ver=4.9.4:14), <anonymous>:27:19)
at c (load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,underscore,customize-base,wp-a11y,wp-util,jquery-ui-core,customize-controls,jquery-ui-widget,jquery-u&load[]=i-mouse,jquery-ui-sortable,jquery-ui-draggable,jquery-ui-droppable,backbone,wp-backbone,jquery-ui-resizable&ver=4.9.4:14)
at load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,underscore,customize-base,wp-a11y,wp-util,jquery-ui-core,customize-controls,jquery-ui-widget,jquery-u&load[]=i-mouse,jquery-ui-sortable,jquery-ui-draggable,jquery-ui-droppable,backbone,wp-backbone,jquery-ui-resizable&ver=4.9.4:18
at f.renderContent (load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,underscore,customize-base,wp-a11y,wp-util,jquery-ui-core,customize-controls,jquery-ui-widget,jquery-u&load[]=i-mouse,jquery-ui-sortable,jquery-ui-draggable,jquery-ui-droppable,backbone,wp-backbone,jquery-ui-resizable&ver=4.9.4:31)
at Object.<anonymous> (load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,underscore,customize-base,wp-a11y,wp-util,jquery-ui-core,customize-controls,jquery-ui-widget,jquery-u&load[]=i-mouse,jquery-ui-sortable,jquery-ui-draggable,jquery-ui-droppable,backbone,wp-backbone,jquery-ui-resizable&ver=4.9.4:31)
at i (load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,underscore,customize-base,wp-a11y,wp-util,jquery-ui-core,customize-controls,jquery-ui-widget,jquery-u&load[]=i-mouse,jquery-ui-sortable,jquery-ui-draggable,jquery-ui-droppable,backbone,wp-backbone,jquery-ui-resizable&ver=4.9.4:2)
at Object.add [as done] (load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,underscore,customize-base,wp-a11y,wp-util,jquery-ui-core,customize-controls,jquery-ui-widget,jquery-u&load[]=i-mouse,jquery-ui-sortable,jquery-ui-draggable,jquery-ui-droppable,backbone,wp-backbone,jquery-ui-resizable&ver=4.9.4:2)
at Function.<anonymous> (load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,underscore,customize-base,wp-a11y,wp-util,jquery-ui-core,customize-controls,jquery-ui-widget,jquery-u&load[]=i-mouse,jquery-ui-sortable,jquery-ui-draggable,jquery-ui-droppable,backbone,wp-backbone,jquery-ui-resizable&ver=4.9.4:31)
at i (load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,underscore,customize-base,wp-a11y,wp-util,jquery-ui-core,customize-controls,jquery-ui-widget,jquery-u&load[]=i-mouse,jquery-ui-sortable,jquery-ui-draggable,jquery-ui-droppable,backbone,wp-backbone,jquery-ui-resizable&ver=4.9.4:2)
at Object.fireWith [as resolveWith] (load-scripts.php?c=0&load[]=jquery-core,jquery-migrate,underscore,customize-base,wp-a11y,wp-util,jquery-ui-core,customize-controls,jquery-ui-widget,jquery-u&load[]=i-mouse,jquery-ui-sortable,jquery-ui-draggable,jquery-ui-droppable,backbone,wp-backbone,jquery-ui-resizable&ver=4.9.4:2)