BIND 9.12.3-P4 crash at dispatch.c:3426: REQUIRE(resp->item_out == 1)

dispatch.c:3426: REQUIRE(resp->item_out == 1) failed, back trace
#0 0x426970 in assertion_failed()+0x60
#1 0x61279a in isc_assertion_failed()+0xa
#2 0x4a5862 in dns_dispatch_getnext()+0x352
#3 0x57292a in rctx_done()+0x17a
#4 0x572db4 in resquery_response()+0x204
#5 0x63606b in run()+0x2bb
#6 0x7f8458968e25 in __do_global_dtors_aux_fini_array_entry()+0x7f8458063c95
#7 0x7f8458692bad in __do_global_dtors_aux_fini_array_entry()+0x7f8457d8da1d
exiting (due to assertion failure)

Please tell me if you need more info. This is running on Centos7, with dnssec-validation = auto. Thanks.