Index: src/org/openstreetmap/josm/data/validation/OsmValidator.java
===================================================================
--- src/org/openstreetmap/josm/data/validation/OsmValidator.java	(revision 16245)
+++ src/org/openstreetmap/josm/data/validation/OsmValidator.java	(working copy)
@@ -234,6 +234,8 @@
             } catch (SecurityException e) {
                 Logging.log(Logging.LEVEL_ERROR, "Unable to load ignored errors", e);
             }
+            // see #19053: remove invalid entry
+            ignoredErrors.remove("3000");
         }
     }
 
Index: src/org/openstreetmap/josm/gui/dialogs/ValidatorDialog.java
===================================================================
--- src/org/openstreetmap/josm/gui/dialogs/ValidatorDialog.java	(revision 16245)
+++ src/org/openstreetmap/josm/gui/dialogs/ValidatorDialog.java	(working copy)
@@ -410,7 +410,9 @@
 
         lastSelectedNode = node;
         if (node != null) {
+            final Set<String> codes = new HashSet<>();
             ValidatorTreePanel.visitTestErrors(node, error -> {
+                codes.add(error.getIgnoreSubGroup()); // see #19053
                 error.setSelected(true);
 
                 hasFixes.set(hasFixes.get() || error.isFixable());
@@ -422,7 +424,7 @@
             });
             selectAction.setEnabled(true);
             if (ignoreAction != null) {
-                ignoreAction.setEnabled(!(node.getUserObject() instanceof Severity));
+                ignoreAction.setEnabled(!(node.getUserObject() instanceof Severity) && codes.size() <= 1);
             }
         }