As soon as your our Gold you have the right to enter the GF lounge, the fact that the lounge agents are unable to verify your status because the BA IT system they are using is slow in updating status is not an excuse to refuse you entrance. Just show your iPad screen with your tier points and go ahead. They might come after you but then you will be inside the lounge and when this happens just ask for a senior management person to come and discuss this issue with you. I have witnessed the above situation a couple of months ago when a lady in front of me had the same probleem, I even proposed to guest her in but she politely declined my offer.