Booking form: tickets is default 1

Suddenly two of my sites′ booking forms is wrong. By default all ticket types is set to 1 and in drop-down selection there is no zero. Result: all customers has to book at least 1 ticket of each typr ??
https://www.sallskapetpromusica.se uses EM 5.10
The other site with same problem https://www.kiviksbio.se/program/space-jam-2/ uses EM 5.10 and EM Pro 2.6.9.2.
The third site work correct with EM 5.10 and EM Pro 2.6.9.2. (https://www.simteater.se/forestallningar/laika-med-ozz-nujen/)

None of the sites uses edited versions of these templetes in the theme.
They do use edited version of bookings-event-printable.php but I can not see it has something to do with this problem.

The page I need help with: [log in to see the link]