Oil indicator does not show oil level

For future readers, my A4 B8 had the same issue, it ended up being that the electronic switch in the bonnet catch was sticking and not detecting that the bonnet is opening. A tell-tale sign in that the “hood ajar” icon won’t be on the dash and hitting the latch with a hammer will unstick it. This happens because the car checks if the bonnet has been open before reading the oil level.