Controlling scatter chart markers in Azure Data Explorer dashboard using KQL

I created a simple scatter chart in my Azure Data Explorer dashboard:

data_delivery_stats
| where isnotempty( dds_date)
| where todatetime( dds_date) between (_startTime .. _endTime) 
| extend str_easting=tolong(dds_easting), str_northing=tolong(dds_northing)

This returns the following map:

The marker shapes and colors are automatically set by ADX. How can I force all markers to share the same shape and color?

This seems possible according to the example given in the Scatter chart documentation but I am unsure how to proceed. The snippet provided in this page does not specify the marker's shapes and colors:

StormEvents
| summarize sum(DamageProperty)by State
| lookup PopulationData on State
| project-away State
| render scatterchart with (xtitle="State population", title="Property damage by state", legend=hidden)

I think the reason is, that you have to have just a table with X and Y Values. In your example out of the docs, you can see, if you do not project-away the States you get the same result:

And if you look into the query:

StormEvents
| summarize sum(DamageProperty)by State
| lookup PopulationData on State

You get this:

Thats why they project-away the state, to get this table:

So the solution is:

You have to project-away all columns except X and Y values, otherwise the scatterchart tries to differentiate between different types of data (e.g.: States).