A new DayBack Package is up on the AppExchange (v1.27). This version updates the API version in the Visualforce and Apex components, including the updates needed for the new SFDC enforcement of “Enable ICU Locale Formats“.
It also has an update that allows DayBack to use the native creation modal without navigating away from DayBack. (Modals like these that were previously difficult to use for record creation in cases were there were lots of required fields.)
To install the new package, either install it from the AppExchange or use this link. You won’t uninstall first and there will be no need to reallocate licenses or reload your customizations: all that sticks. (If you’ve embedded DayBack on a record’s Salesforce page, that customization is unaffected by the new package and won’t be clobbered.)