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