Unable to add outgoing webhook integration

I’d like to add an outgoing webhook from Gitlab to mattermost. As administrator i can do this for the instance but when I navigate down via the project Settings->Integrations->Mattermost Notifications and try to edit the any settings, including webhook I’m blocked from changing.

I have administrator role.

I know this was working before as I have used it and managed to have notifications delivered to specific channels.

Gitlab 14.7.3
Ubuntu 20.04.5 LTS