I’ve always referred to this as “hitting the wall.” At least you can make into an advanced stage of learning! I get stuck in the intermediate phase and stay there.
I will acquire an interest in a subject, and immediately learn all I can about it. Soon I become obsessively involved, to the point where I am thinking about my newfound interest constantly and at inappropriate times. Eventually, I hit the wall and I can’t absorb any additional information. The learning process stops, frustration sets in, the interest stagnates and then fades into the background, replaced by something else.
My interests are never entirely lost and eventually they return, but in a subdued state and lacking the original intensity.
I as well have never mastered anything. I wish I could recommend something to help! Hopefully I won’t appear overly negative by saying this, but in my case, I am beginning to accept that this is trait is immutable.