--- old/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp	2020-04-22 11:59:03.632925483 +0200
+++ new/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp	2020-04-22 11:59:03.424925406 +0200
@@ -2294,6 +2294,7 @@
       if (r->is_active() && !r->is_cset()) {
         _heap->marked_object_oop_iterate(r, &cl, update_watermark);
       }
+      r->set_update_watermark(r->bottom());
       if (ShenandoahPacing) {
         _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
       }