There would appear to be a definite problem in the Scatter Chart visual where sorting has been set by the value on the X-Axis, and there is a specified category in the "Legend". The sorting ap...
I am not sure what else you need - I supplied a link to a sample PBIX that shows the issue.
The sorting for the visual is by the Month-Year.
The Data Behind the visual orders correctly.
The Visual itself though and the X - Axis is not in the Month Year order its being told to sort in.
It appears as though the Visual sorts by the legned field first, then Month-Year.
This is incorrect