Adding a custom script with an IPv4 reference causes IPv6 rules to fail to apply #1493

Describe the bug
Add a custom startup script with only one IPv4 entry. (IPv6 support enabled)
$IPTABLES -A "afwall" --destination "1.1.1.1" -j RETURN

The IPv6 rule counter hangs when applying rules, and IPv6 app rules aren't added as seen with:
ip6tables -S

Confirmed IPv4 application rules are added and confirmed with
iptables -S

Tested with AFWall 4.0.1 and AFWall 4.0.3

Firewall Logs
Relevant logs (scrubbed for PII)

I/AFWall ( 7595): Successfully applied IPv6 rules
I/AFWall ( 7595): Successfully applied all firewall rules
I/AFWall6 ( 7595): command '$IPTABLES -A "afwall" --destination "1.1.1.1" -j RETURN' exited with status 2

Smartphone (please complete the following information):

• Device: OP8T
• Android OS: LOS 23.2

Additional context
Also logcat will show failure with using straight iptables commands
iptables -A "afwall" --destination "1.1.1.1" -j RETURN

I don't believe AFWALL6 should be processing IPv4 rules in the custom startup script?
D/AFWall6 ( 7595): command 'iptables -A "afwall" -p udp --dport 53 -j RETURN' exited with status 4, retrying (attempt 9/10)
D/AFWall6 ( 7595): command 'iptables -A "afwall" -p udp --dport 53 -j RETURN' exited with status 4, retrying (attempt 10/10)