In a loop topology like:

sudo mn --controller=remote,ip=192.168.0.1 --custom customtopo.py --topo ring --switch ovsk,protocols=OpenFlow13

Most of the times the flows are correct when a link is blocked (s1-3 and s3-3):

vagrant@mininet-vm-ubuntu-25:~\> sudo ovs-ofctl dump-flows s1 -O OpenFlow13
OFPST_FLOW reply (OF1.3) (xid=0x2):
cookie=0x2b00000000000025, duration=13.623s, table=0, n_packets=7, n_bytes=595, priority=100,dl_type=0x88cc actions=CONTROLLER:65535
cookie=0x2b0000000000013f, duration=10.598s, table=0, n_packets=8, n_bytes=560, priority=2,in_port=2 actions=output:1
cookie=0x2b00000000000140, duration=10.598s, table=0, n_packets=2, n_bytes=140, priority=2,in_port=1 actions=output:2,CONTROLLER:65535
cookie=0x2b00000000000025, duration=13.623s, table=0, n_packets=15, n_bytes=1238, priority=0 actions=drop

vagrant@mininet-vm-ubuntu-25:~\> sudo ovs-ofctl dump-flows s2 -O OpenFlow13
OFPST_FLOW reply (OF1.3) (xid=0x2):
cookie=0x2b00000000000026, duration=51.585s, table=0, n_packets=20, n_bytes=1700, priority=100,dl_type=0x88cc actions=CONTROLLER:65535
cookie=0x2b00000000000141, duration=48.562s, table=0, n_packets=4, n_bytes=280, priority=2,in_port=1 actions=output:3,output:2
cookie=0x2b00000000000142, duration=48.562s, table=0, n_packets=4, n_bytes=280, priority=2,in_port=3 actions=output:1,output:2
cookie=0x2b00000000000143, duration=48.562s, table=0, n_packets=2, n_bytes=140, priority=2,in_port=2 actions=output:1,output:3,CONTROLLER:65535
cookie=0x2b00000000000026, duration=51.585s, table=0, n_packets=12, n_bytes=1020, priority=0 actions=drop

vagrant@mininet-vm-ubuntu-25:~\> sudo ovs-ofctl dump-flows s3 -O OpenFlow13
OFPST_FLOW reply (OF1.3) (xid=0x2):
cookie=0x2b00000000000024, duration=55.580s, table=0, n_packets=24, n_bytes=2040, priority=100,dl_type=0x88cc actions=CONTROLLER:65535
cookie=0x2b00000000000144, duration=52.552s, table=0, n_packets=2, n_bytes=140, priority=2,in_port=2 actions=output:1,CONTROLLER:65535
cookie=0x2b00000000000145, duration=52.552s, table=0, n_packets=8, n_bytes=560, priority=2,in_port=1 actions=output:2
cookie=0x2b00000000000024, duration=55.594s, table=0, n_packets=15, n_bytes=1226, priority=0 actions=drop

However some times we see flows for blocked links (s1-3 and s3-3):

vagrant@mininet-vm-ubuntu-25:~\> sudo ovs-ofctl dump-flows s1 -O OpenFlow13
OFPST_FLOW reply (OF1.3) (xid=0x2):
cookie=0x2b00000000000021, duration=40.776s, table=0, n_packets=18, n_bytes=1530, priority=100,dl_type=0x88cc actions=CONTROLLER:65535
cookie=0x2b00000000000122, duration=36.742s, table=0, n_packets=19789, n_bytes=1385230, priority=2,in_port=3 actions=output:2,output:1
cookie=0x2b00000000000129, duration=34.215s, table=0, n_packets=14992, n_bytes=1049440, priority=2,in_port=2 actions=output:1
cookie=0x2b0000000000012a, duration=34.215s, table=0, n_packets=6, n_bytes=420, priority=2,in_port=1 actions=output:2,CONTROLLER:65535
cookie=0x2b00000000000021, duration=40.760s, table=0, n_packets=14, n_bytes=1164, priority=0 actions=drop

vagrant@mininet-vm-ubuntu-25:~\> sudo ovs-ofctl dump-flows s2 -O OpenFlow13
OFPST_FLOW reply (OF1.3) (xid=0x2):
cookie=0x2b00000000000023, duration=36.845s, table=0, n_packets=14, n_bytes=1190, priority=100,dl_type=0x88cc actions=CONTROLLER:65535
cookie=0x2b0000000000012b, duration=30.291s, table=0, n_packets=19797, n_bytes=1385790, priority=2,in_port=1 actions=output:3,output:2
cookie=0x2b0000000000012c, duration=30.291s, table=0, n_packets=14984, n_bytes=1048880, priority=2,in_port=3 actions=output:1,output:2
cookie=0x2b0000000000012d, duration=30.291s, table=0, n_packets=6, n_bytes=420, priority=2,in_port=2 actions=output:1,output:3,CONTROLLER:65535
cookie=0x2b00000000000023, duration=36.845s, table=0, n_packets=13, n_bytes=1086, priority=0 actions=drop

vagrant@mininet-vm-ubuntu-25:~\> sudo ovs-ofctl dump-flows s3 -O OpenFlow13
OFPST_FLOW reply (OF1.3) (xid=0x2):
cookie=0x2b00000000000022, duration=30.807s, table=0, n_packets=12, n_bytes=1020, priority=100,dl_type=0x88cc actions=CONTROLLER:65535
cookie=0x2b00000000000126, duration=26.797s, table=0, n_packets=14980, n_bytes=1048600, priority=2,in_port=3 actions=output:2,output:1
cookie=0x2b0000000000012e, duration=24.266s, table=0, n_packets=2, n_bytes=140, priority=2,in_port=2 actions=output:1,CONTROLLER:65535
cookie=0x2b0000000000012f, duration=24.266s, table=0, n_packets=19805, n_bytes=1386350, priority=2,in_port=1 actions=output:2
cookie=0x2b00000000000022, duration=30.807s, table=0, n_packets=14, n_bytes=1176, priority=0 actions=drop