Index: trunk/test/unit/org/openstreetmap/josm/gui/dialogs/relation/MemberTableModelTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/gui/dialogs/relation/MemberTableModelTest.java	(revision 18437)
+++ trunk/test/unit/org/openstreetmap/josm/gui/dialogs/relation/MemberTableModelTest.java	(revision 18439)
@@ -2,17 +2,26 @@
 package org.openstreetmap.josm.gui.dialogs.relation;
 
+import static org.junit.jupiter.api.Assertions.assertAll;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
+import java.util.stream.Stream;
 
+import org.junit.jupiter.api.Test;
+import org.openstreetmap.josm.TestUtils;
+import org.openstreetmap.josm.data.coor.LatLon;
+import org.openstreetmap.josm.data.osm.DataSet;
 import org.openstreetmap.josm.data.osm.Node;
 import org.openstreetmap.josm.data.osm.OsmPrimitive;
+import org.openstreetmap.josm.data.osm.Relation;
+import org.openstreetmap.josm.data.osm.RelationMember;
 import org.openstreetmap.josm.data.osm.Tag;
+import org.openstreetmap.josm.gui.layer.OsmDataLayer;
 import org.openstreetmap.josm.gui.tagging.presets.TaggingPresetHandler;
 import org.openstreetmap.josm.testutils.annotations.BasicPreferences;
-
-import org.junit.jupiter.api.Test;
 
 /**
@@ -35,7 +44,59 @@
             @Override
             public Collection<OsmPrimitive> getSelection() {
-                return Collections.<OsmPrimitive>singleton(n);
+                return Collections.singleton(n);
             }
         }).getRelationMemberForPrimitive(n));
     }
+
+    /**
+     * Non-regression test for JOSM #12617, #17906, and #21889. Regrettably, it was not easily possible to test using
+     * drag-n-drop methods.
+     */
+    @Test
+    void testTicket12617() {
+        final Node[] nodes = new Node[10];
+        for (int i = 0; i < nodes.length; i++) {
+            nodes[i] = new Node(LatLon.ZERO);
+            // The id has to be > 0
+            nodes[i].setOsmId(i + 1, 1);
+        }
+        final Relation relation = TestUtils.newRelation("", Stream.of(nodes).map(node -> new RelationMember("", node))
+                .toArray(RelationMember[]::new));
+        final OsmDataLayer osmDataLayer = new OsmDataLayer(new DataSet(), "testTicket12617", null);
+        osmDataLayer.getDataSet().addPrimitiveRecursive(relation);
+        final MemberTableModel model = new MemberTableModel(relation, osmDataLayer, new TaggingPresetHandler() {
+            @Override
+            public Collection<OsmPrimitive> getSelection() {
+                return Collections.singleton(relation);
+            }
+
+            @Override
+            public void updateTags(List<Tag> tags) {
+                // Do nothing
+            }
+        });
+
+        model.populate(relation);
+        // Select the members to move
+        model.setSelectedMembersIdx(Arrays.asList(2, 3, 5, 9));
+        // Move the members (this is similar to what the drag-n-drop code is doing)
+        model.addMembersAtIndexKeepingOldSelection(model.getSelectedMembers(), 2);
+        model.remove(model.getSelectedIndices());
+        // Apply the changes
+        model.applyToRelation(relation);
+
+        // Perform the tests
+        assertAll(() -> assertEquals(10, relation.getMembersCount(), "There should be no changes to the member count"),
+                () -> assertEquals(nodes[0], relation.getMember(0).getMember()),
+                () -> assertEquals(nodes[1], relation.getMember(1).getMember()),
+                () -> assertEquals(nodes[2], relation.getMember(2).getMember(), "Node 2 should not have moved"),
+                () -> assertEquals(nodes[3], relation.getMember(3).getMember(), "Node 3 should not have moved"),
+                () -> assertEquals(nodes[4], relation.getMember(6).getMember(), "Node 4 should be in position 5"),
+                () -> assertEquals(nodes[5], relation.getMember(4).getMember(), "Node 5 should be in position 4"),
+                () -> assertEquals(nodes[6], relation.getMember(7).getMember(), "Node 6 should not have moved"),
+                () -> assertEquals(nodes[7], relation.getMember(8).getMember()),
+                () -> assertEquals(nodes[8], relation.getMember(9).getMember()),
+                () -> assertEquals(nodes[9], relation.getMember(5).getMember(), "Node 9 should have moved")
+                );
+    }
 }