Problems with Customize

Switched to “Customize”, customized the sidebar, clicked “Save”: “Updated ajax save widget” was shown in the widget. On the page itself, no sidebar was displayed. Clicked the “Update” button to save the Page, and on loading, there were no widgets in the customized sidebar. Had to recreate all widgets.

“TypeError: pwMediaWidgets.handleWidgetAdded is not a function”
This error appears in console at random times.