Variable product pages suddenly display incorrectly

Hi, All my standard WooCommerce products display correctly e.g. https://larissaeremeeva.com/artwork/all-quiet-within/ However, variable products have suddenly stopped displaying correctly e.g. https://larissaeremeeva.com/artwork/print-all-quiet-within/. Not only that, but in WOrdPress admin mode, the top WordPress tool bar also disappears. I thought this might be due to recently installed plug-ins (Popup Maker and RankMath), so I deactivated them but the problem persists. Have you any ideas what the cause is and how to fix? Thanks!