Weils so schön war der nächste Hotfix.
Zitat
An issue has been identified in the 7.7.0 release - published on 21st January, 2019 that causes invoices generated by orders or the daily automation tasks not to receive the custom invoice format specified in the new Tax Configuration interface.
A second issue has been identified whereby an SQL error occurs when invoicing time entries in the Project Management Addon when Continuous Invoice Generation mode is enabled.
CORE-13106 & PMA-136 - Custom Invoice Numbering and Invoice Time Entries 1.0.0