L2tp load-balance has no data

vyos version is v1.3.2
There are two l2tp links running on a physical link. l2tp performs load balancing. After taking effect, load balancing can be achieved. But one minute later, only one l2tp has data and the other has no data.

my configure:
set load-balancing wan interface-health l2tpeth1111 failure-count ‘3’
set load-balancing wan interface-health l2tpeth1111 nexthop ‘10.100.100.1’
set load-balancing wan interface-health l2tpeth1111 success-count ‘1’
set load-balancing wan interface-health l2tpeth1111 test 10 resp-time ‘5’
set load-balancing wan interface-health l2tpeth1111 test 10 target ‘33.33.33.33’
set load-balancing wan interface-health l2tpeth1111 test 10 ttl-limit ‘1’
set load-balancing wan interface-health l2tpeth1111 test 10 type ‘ping’

set load-balancing wan interface-health l2tpeth2222 failure-count ‘4’
set load-balancing wan interface-health l2tpeth2222 nexthop ‘10.100.110.1’
set load-balancing wan interface-health l2tpeth2222 success-count ‘1’
set load-balancing wan interface-health l2tpeth2222 test 10 resp-time ‘5’
set load-balancing wan interface-health l2tpeth2222 test 10 target ‘33.33.33.33’
set load-balancing wan interface-health l2tpeth2222 test 10 ttl-limit ‘1’
set load-balancing wan interface-health l2tpeth2222 test 10 type ‘ping’

set load-balancing wan rule 10 inbound-interface ‘eth3’
set load-balancing wan rule 10 interface l2tpeth1111 weight ‘2’
set load-balancing wan rule 10 interface l2tpeth2222 weight ‘1’
set load-balancing wan rule 10 per-packet-balancing
set load-balancing wan rule 10 protocol ‘all’