Option to disable/block IPv6 in OpenVPN settings doesn't survive reboot

REPRODUCIBILITY (% or how often): 100%
BUILD ID = OS VERSION (Settings > About product): 4.3.0.12
HARDWARE (XA2, X10, X10 II, …): XA2
UI LANGUAGE: German
REGRESSION: (compared to previous public release: Yes, No, ?): Setting wasn’t available in previous releases

DESCRIPTION:

The newly introduced option to deactivate IPv6 in the VPN settings is only saved as long as the system is not restarted. After a reboot, it is set to “default” again and IPv6 is no longer blocked, resulting in an IPv6 leak.

I have only tried this with OpenVPN, so I can’t say whether the problem also occurs with other VPN protocols.

PRECONDITIONS:

Configure an OpenVPN connection (in my case: Mullvad VPN using the .ovpn file provided at their webseite)

STEPS TO REPRODUCE:

  1. Go to the settings of a saved OpenVPN configuration and change the “disable IPv6” setting to Yes
    → Everything works as expected, IPv6 is disabled.
  2. Reboot the phone
  3. Go to the settings again, reconnect the VPN

EXPECTED RESULT:

IPv6 is still disabled in VPN settings

ACTUAL RESULT:

“Disable IPv6” is reverted to “Standard”, IPv6 isn’t blocked anymore after reconnecting the VPN

ADDITIONAL INFORMATION: