The problem is that all labels (in my case "ProductCustomsFieldCart" custom field type "image") have the same "for" attribute value, so clicking on any of the images selects first input (radio button)
File "/administrator/components/com_virtuemart/models/customfields.php" @ line 964
OLD CODE
for="' . $productCustom->virtuemart_custom_id .$row. '"
NEW CODE
for="' . $productCustom->virtuemart_customfield_id .$row. '"