I have a similar problem with the product short description / excerpt. It shows raw html text and changes to that field are not saved.
A workaround solution was to disable the visual editor globaly in my profile. But because I need the visual editor for other fields, I disabled tinymce for the excerpt editor:
woocommerce\includes\admin\post-types\meta-boxes\class-wc-meta-box-product-short-description.php
replace
'tinymce' => array(
'theme_advanced_buttons1' => 'bold,italic,strikethrough,separator,bullist,numlist,separator,blockquote,separator,justifyleft,justifycenter,justifyright,separator,link,unlink,separator,undo,redo,separator',
'theme_advanced_buttons2' => '',
)
with
'tinymce' => false,
