Sorting azure map legend entries by column not working

For the Azure Map visual, I'm observing the same bug that Rob35 posted about - Legend sort is driven by the Size field values; it reverts to the regular Sort by column order when the Size field is emptied. 

Other Built-in Power BI visuals eg Bar Chart offer control over Legend sorting by the "..." menu at the top-right corner of each visual's frame. But they only offer to sort asc or desc by the Sort by column.

Sorting any visual's Legend by values is rather odd - can't think when I would want that. The Legend should not attempt to convey information about the values, and dynamically re-sort when slicers etc are used. That will confuse users.  I'll raise a support case.