Configure third interface by gui.
Configures all standard parameters prompts to save. But it just keeps rolling.
But by option 2 (Set interface (s) IP address) it works normal.
Dropping a note here to match what I put on the bug report you opened:
I tried this a couple times and it always worked for me. If you can reproduce it again, take notes of the exact steps performed and exactly when contact was lost with the firewall and which parts of the process were saved and which had to be performed again.