ipvsadm doesn't report running backup-threads because of a bug in libipvs. I've already attached two patches to bug #403133 for keepalived, which holds it's own copy of libipvs. Reproducible: Always
I can confirm these issues, and that the attached patches resolve the issues described.
0001-libipvs-Fix-reporting-of-the-state-of-the-backup-dae.patch added to ipvsadm now, since it got lost before; the others are no longer needed.