Hi Ad,
but in the Geography Taxonomy that is bundled with the standard samples for EDG, the Concept Hierarchy does render custom icons:
This is implemented using dash:IconRole as:
g:Country-flag
a sh:PropertyShape ;
sh:path g:flag ;
dash:propertyRole dash:IconRole ;
rdfs:comment "The values of this property are basically copied over from the corresponding property P41 at the Wikidata entity that is linked to this country." ;
sh:nodeKind sh:IRI ;
sh:order "100"^^xsd:decimal ;
sh:values [
sh:path wdt:P41 ;
sh:nodes [
sh:path g:wikidataCountry ;
] ;
] ;
.
Does this look different from your declarations? (You may need to reload the browser after making changes as the presence of icons is cached).
Holger