Error when changing VPN to "Nailed Up"

When the VPN is added to Zone LAN (or any other zone with a physical interface), I cannot change Phase 2 Initiation from Auto to Nailed Up.

The VPN is deactivated and not connected.

When it's added to IPSec_VPN I can change any time.

Also please tell your web designer to not make the error dialogs a fixed height. Set CSS minimum-height and then let the content scale the box to 80% viewport-height if it must.