On checkout, the counter for the breakfast add-on does not go above 1, even when the booking has multiple guests.
Why this happens. The counter behavior comes from how the add-on is configured in Guesty. When an add-on is set to per guest per night in Guesty, selecting it once covers all guests for all nights. The counter stays at 1, and the total multiplies automatically by the number of guests and nights.
What you can do. To make this clear to your guests, rename the add-on in Guesty to something like "Breakfast (per person per night)". The site picks up the new name on the next sync.