Apparently it has something to do with different calendars sharing the same Extra settings and discount settings. It works when there no such sharing
after adding these css lines I can see it again
button.single_add_to_cart_button.button.alt {
display: block !important;
}
The problem is I can’t select any date / even if the date is set as available I will obtain the error “The period you selected is not available anymore”
It turns out it was a completely unreletad problem, a collaborator messing with the fb account.
The plugin is working just fine.
