This was caught by the new IPMP test suite: when an IPv6 IPMP interface comes up, ipif_ndp_start_dad() erroneously restricted its ndp_lookup_v6() to the IPMP interface, but since IPv6 NCEs (even for the IPMP interface) are tied to the underlying interfaces, this silently failed, causing ipif_ndp_start_dad() to silently bail. The fix is a one-liner:
http://zhadum.east/export/ws/clearview/clearview-ipmpdev/dad-fix -- meem
