Import symbology definition from .avl results in blank symbols for polygon shp in ArcMap 10.7.1
I have an old Arc View legend file (.avl).
I would like to use it to symbolize my polygonal shapefile in ArcMap 10.6.1.
The symbology is set on a single field using the method "By Category".
From the Symbology window within the properties of my polygonal layer, I press Import and then I select my avl file from the option "Import symbology definition from anArc View 3 legend file (*.avl)".
Then I select the right field, and the list of values appear.
However, the symbols are all blanks.
In the official docs http://desktop.arcgis.com/en/arcmap/latest/map/working-with-layers/importing-symbology-from-another-... I don't see any limits regarding this type of import, except for some cases which do not seem mine however (highlighted in the picture below).
Thanks for any help.
P.S. I had to post this thread selecting "ArcGIS Pro" group as there was no possible choice regarding ArcMap/ArcGIS Desktop...
