I suspect custard is right that moisture has got trapped in the finish. He's also right to urge caution. But you might just try one technique on a small less conspicuous area, if there is one, and if it works then perhaps expand the on the surface you work on.
Get a good sized handful of cotton wool, and gently wrap a clean white cotton cloth (e.g., handkerchief) around it. Make it into roughly a sausage shape with no creases in the surrounding cloth. Add some alcohol (meths) to the cotton wool, just enough that when you squeeze the sausage the handkerchief becomes moist, not dripping.
Then, with a gently swinging motion ranging through about 2 - 3" in the same direction as the box's length, lightly let the cloth just barely brush the surface of the polish, i.e., swing down, touch, swing off, then the same in the other direction. Swing backwards and forwards like this maybe half a dozen times and examine the result. If the cloudiness has diminished, do a bit more, and if the cloudiness disappears leaving a clear polish, you may have found the cure - if you're feeling confident you might tackle the whole box. If this initial test makes no difference, then the existing polish is unlikely to be either shellac, or possible one of the other finishes that alcohol can quite often soften enough to release trapped moisture, e.g., pre-cat lacquer, and fixing the problem becomes more challenging, probably out of the reach of a simple home cure, thus falling into the realm of a skilled restorer or polisher. Slainte.
