Got it to work! So yes, I had synced the app and regenerated the table before. The issue was I had set the VIRTUAL COLUMN for DECIMALDURATIONS to NOT SHOW as I don’t want to see this value in my table. The group by aggregate SUM :: DECIMALDURATIONS does not show if the SHOW is off. When I toggled the DECIMALDURATIONS to SHOW, and then went back to the UX > CHART > GROUP AGGREGATE the SUM :: DECIMALDURATIONS appears. This is interesting, not sure if you see the same thing?
There may be a hack to this. If I SHOW the column, then go to the UX and group aggregrate by SUM :: DECIMALDURATION, then go back to the column and turn of SHOW, it looks like the chart still remains SUM :: DECIMALDURATION.
Separately, I think it would be more beneficial if the X axis was not a decimal number and rather in the 00:00:00 format. It’s hard for a user to know how many hours and minutes and seconds 6.25 is (for example). Wonder if this is just an AppSheet capabilitiy issue of not being able to show 00:00:00 in the x-axis.