You should be able to get what you want with a dual-axis chart with multiple mark types.
1. Create Calculated Field: Zero-day Milestone
Right-click on GA Launch Date > Create cal. field. >
IF [Duration] == 0 THEN [GA LAUNCH_DATE] END
2. Add to view
Convert this new field to continuous (right-click on dimension), add to the view next to GA Launch Date pill, select Month detail level to match first pill.
3. Create view
3.1. Right-click Zero-day Milestone pill > Dual Axis
3.2. Right-click top axis > Synchronize Axis and then uncheck Show Header
3.3. On Marks shelf > Select Multiple Mark Types
3.4. Scroll to Marks for Zero-day, select shape, remove size pill, and select the shape you want, adjust size to hide the underlying Gantt bar.
If the underlying zero-day gantt lines bother you, you could create a new calculated field for GA Launch Date that includes only non-zero duration events.
See attached workbook.
Test gantt_jimw.twbx.zip 54.3 KB
Thank you Jim. That is exactly what I am looking for. I am going to give it a try later this weekend. Thank you so much for the response!
Worked like a charm Jim. Thank you again!