This appears to happen even with a basic masquerade rule.
rule 3 { description "RCF1918 172.12/12" outbound-interface eth0 source { address 192.168.0.0/16 } translation { address masquerade } }
admin@edge:~$ show nat source rules Traceback (most recent call last): File "/usr/libexec/vyos/op_mode/show_nat_rules.py", line 73, in <module> srcdest_json = dict_search('match.right', data['expr'][i]) IndexError: list index out of range