Colored polygon outlines displayed as just all white opaque polygons - kml

Question

Someone shared a kml with me that was created in Google Earth Web along with a screenshot of it.
When I opened it up in Google Earth Pro, the colored polygons displayed as solid white.
For a test, I created a test polygon in Google Earth Web and exported it as KML.
Projects > New project > Create KML file
Draw line or shape > create polygon
Set fill color red at 75%
Set color 4px
Select export as KML
Same thing, the polygon shows up as a white box in Google Earth Pro.
The exported KML is structured like this:
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns=http://www.opengis.net/kml/2.2 xmlns:gx=http://www.google.com/kml/ext/2.2 xmlns:kml=http://www.opengis.net/kml/2.2 xmlns:atom=http://www.w3.org/2005/Atom>
<Document>
<name>Untitled Project</name>
<gx:CascadingStyle kml:id="__managed_style_147D324643211BD21CEE">
<Style>
<IconStyle>
<Icon>
<href>https://earth.google.com/earth/rpc/cc/icon?color=1976d2&id=2000&scale=4</href>
</Icon>
<hotSpot x="64" y="128" xunits="pixels" yunits="insetPixels"/>
</IconStyle>
<LabelStyle>
</LabelStyle>
<LineStyle>
<color>ffa21f7b</color>
<width>3.63636</width>
</LineStyle>
<PolyStyle>
<color>c02f2fd3</color>
</PolyStyle>
<BalloonStyle>
<displayMode>hide</displayMode>
</BalloonStyle>
</Style>
</gx:CascadingStyle>
...
<StyleMap id="__managed_style_0C1991940B211BD21CEE">
<Pair>
<key>normal</key>
<styleUrl>#__managed_style_147D324643211BD21CEE</styleUrl>
</Pair>
<Pair>
<key>highlight</key>
<styleUrl>#__managed_style_2EB2C27FFE211BD21CEE</styleUrl>
</Pair>
</StyleMap>
<Placemark id="09A507D5E3211BD1D53F">
<name>Test Polygon</name>
<styleUrl>#__managed_style_0C1991940B211BD21CEE</styleUrl>
<Polygon>
<outerBoundaryIs>
<LinearRing>
<coordinates>
0.0287244781654028,51.5286273373769,4.888032506075639 0.03124375777183053,51.52899071640604,5.649232085770059 0.03060716674301966,51.5305703663013,6.296306355936279 0.02835525808849049,51.53027540191405,5.649128389213159 0.0287244781654028,51.5286273373769,4.888032506075639
</coordinates>
</LinearRing>
</outerBoundaryIs>
</Polygon>
</Placemark>
</Document>
</kml>
The <gx:CascadingStyle> does not appear in the KML reference.
https://developers.google.com/kml/documentation/kmlreference
What is going on here?
i am expecting the original colored polygon to appear in Google Earth Pro.

Answer 1

The <gx:CascadingStyle> is an undocumented element that is created in Google Earth Web that is unsupported by Google Earth Pro.
If you make a minor edit to the KML, then it will work as expected.
Make these changes:
Remove <Style> and </Style> elements.
Globally change <gx:CascadingStyle kml:id="xxx"> to <Style id="xxx">.
Replace <gx:CascadingStyle kml:id= with <Style id=
Replace </gx:CascadingStyle> with</Style>
Example:
Old:
<gx:CascadingStyle kml:id="__managed_style_147D324643211BD21CEE">
<Style>
...
</Style>
</gx:CascadingStyle>
New:
<Style id="__managed_style_147D324643211BD21CEE">
...
</Style>
You can globally make the changes to the KML using a text editor; e.g. Notepad++.
The KML is now valid with respect to the OGC KML 2.2 standard and will work in Google Earth Pro.