We've upgraded from 2.2.8 to 2.2.11 this morning.
1st issue : we had to had /app/design/frontend/vendor/theme/Magento_Catalog/templates/product/view/gallery.phtml becuase it throws a fatal error (about the new function getOptionsJson()
"options": <?= /* @noEscape */ $block->getGalleryOptions()->getOptionsJson() ?>,
now it show everything except the thumbnails.
any idea?