Searched Bug List for "Add Work Unit", nothing found.
WorkingHours version: 2.19.17.0
OS + version: Win11, version 22H2, OS build 22621.674, 64-bit
After adding a Work Unit on a date of choice (not today), without exiting the program, if you want to add another work unit for a specified date, it will not allow you. Todays date remains in the field.
Work around: Save description, details, task, times, etc. in todays date, open up the Work Unit again, change date to date of choice.