Oh man that's terrible news
I called NATS the other day and it seems that there isn't an obvious correlation between how many Ishihara plates one can see and how well they do on their CAD test. I decided I'm going to go to City University and take the tests there as they invented CAD in the first place. NATS also accepts a pass if you pass in City.
Is that not the CAD test? It only disappears for a few seconds in my case... but people have been pointing out that this isn't what it really looks like or is easier than the actual.