User snippet categories do not appear in SQL Developer Snippets window. But user snippets do appear under Edit Snippets.
Completely uninstalling GeoRaptor from Tools\Features\Installed Updates restores the ability to view user snippets.
my workaround: install GeoRaptor on slightly older version of SQL Developer and use latest version of SQL Developer when not using GeoRaptor.
Affects SQL Developer 20.4.1.407, 21.4.1, 21.4.2, 21.4.
User snippets before installing georaptor

User snippets after installing georaptor

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