The conflict can be, if the theme is using Bootstrap library and version of Bootstrap is different then version in Booking Calendar. Booking Calendar is use bootstrap library 3.3.5
Such conflict can make issue of opening and immediate closing some interface elements (like drop down lists or modal windows), or issue with showing tooltips or popovers, etc...
How to fix?
Then Save the changes and test it.
Please note, in this case, possible issues with not showing mouse over tooltips at the front-ens side in Booking Calendar. Its tooltips for showing booking data, times and cost, when mouse over specific day.