[Bug] PowerChart rangeStartDate and rangeEndDate not working

In the docs for PowerChart it says:

  • rangeStartDate: Start date for the modified chart data range that the user has selected, either with the range brush or by panning/zooming. Read-only. Value is date.
  • rangeEndDate: End date for the modified chart data range that the user has selected either with the range brush or by panning/zooming. Read-only. Value is date.

but these values seem to only ever depend on the panning/zooming? Selecting range brushes doesn't seem to do anything, and I need these starts and ends for some scripting I'm doing. Is this a bug?

Running on an 8.1.43 Gateway