Booking time slot not recursive

Hello. We have set the Booking time slot from initial 1 hour min., to the final as 3 weeks.

But, there are times it gets desconfigured, we dont change anything and it only gives us 1-2 days of time slots.

Like, I had saved the settings this past monday. Then last day to book open was at 6th of next month (we dont have weekends active). Today I checked and last day was still the 6th. I saved again and next day (9th) was available to book. If I dont save the settings again the next days, it will keep the 9th as last day.

How can I solve this?