After upgrading to the latest version (2015.2.729.45) , I noticed a few changes:
- The columns no longer show "undefined". They just show blanks.
- Turning AutoGenerateColumns="true" now shows both the generated columns and the declared columns.
- Changing my DataFields to use the gantt chart's field names instead of my column names fixes the issue!
So, for the DataField="Naziv" in Tomislav's example, it should instead be DataField="Title"!
That makes no sense to me, as I would expect the DataField names to come from my data source just like they do in every other ASP.NET AJAX control, but now that I know what's going on, I can work around it.