Group headings don't display properly for scatter charts

Since the last update, my scatter chart labels have stopped displaying correctly. My set up is:

Fields:

Collection name (simple text field, grouped)
Labels (simple text field)
Data (numeric field)

The setup is correct in table view, and displays properly in all other chart formats, with the legend showing all of the collection names in order (eg: 1 thing, 2 thing, 3 thing). But in scatter charts, it repeats the last item in the collection each time (eg: 15 thing, 15 thing, 15 thing).

Everything else checks out - the number of items expected, and the labels and data are both performing exactly where I expect them to be. It was working fine, now it isn't.

I thought perhaps it was an aggregation issue, but that's not the case, and it does work with all other chart types. I'm not showing any errors, either in my console or in my dlog.

Thoughts on how I might troubleshoot this further?