Hi @Christina284
It's possible you are experiencing what many hosts have been dealing with since the Summer release with opening days, blocking days, setting custom minimum stays, removing previous custom minimum stays and custom pricing. Did you possibly have previous custom minimum stay settings on the dates you're trying to open? When you hover over the date, what does the right side panel say?
You may have to turn on Pro Tools and use Rule Sets to override the "stuck" calendar settings and set new ones. Pro Tools are available to all hosts now (previously only hosts with 6 or more properties could use it). Below is a guide on how to use Pro Tools and Rule Sets on your calendar. It has screen shots to help you:
How to Use Pro Tools and Rule Sets
https://community.withairbnb.com/t5/Community-Guides/GUIDE-Use-Pro-Tools-to-Set-Calendar-Custom-Pric...
Not sure if this will help? Let us know how it goes!