I don't see any errors in VyOS 1.3-stable-202308240442
vyos@r1# set firewall group network-group FW-OUT network '191.200.161.8/31' [edit] vyos@r1# set firewall group network-group FW-OUT network '191.200.161.8/32' [edit] vyos@r1# commit [edit] vyos@r1# delete firewall group [edit] vyos@r1# commit [edit] vyos@r1#