The Custom Field Editor saves the content but not displaying it if you edit again the product.
in administrator/components/com_virtuemart/models/customfields.php (line 601)
change
return $editor->display('field['.$row.'][customfield_value]',$field->custom_value, '550', '400', '60', '20', false).'</td><td>';
to
return $editor->display('field['.$row.'][customfield_value]',$field->customfield_value, '550', '400', '60', '20', false).'</td><td>';
problem still continues on 2.9.9.4
I also noticed that custom customfield_value in the __virtuemart_product_customfields is varchar type so when you put a lot of data in the editor it may cut it down to its size and cause problems in the pages displayed in fronted and admin also
Thank you for the reminder and fix. Added.
Yes, joined tables using only fixed table sizes are up to 20% faster. You can set these fields to text, using dblayoutstrict=0 in virtuemart.cfg. Store the config and use the database update tool.