Gantt Chart not showing all items

Having a problem with the Gantt view in one of our product boards. Trying to built a view that shows the stack of launch dates for product features, and the Gantt is only showing 7 of 15 items in the group we’ve designated. There is data in the launch date column for items that are not showing, so something is inconsistent.

No filters are on, and the data is accurate for the 7 items selected. And it’s a random set of the 7. Need some help. We’ve reloaded the pages, deleted the widgets and re-created, and getting the same result. Also, that error message in the one snip? Didn’t show up in my Chrome browser, but did show up when I snipped?