Where did the Distort Filters go?

I just ran into this issue when trying to create a twirl (you know me!) and wanted to share the resolution.

Problem: Some of the Distort filters are unavailable.  When you try to use the Pinch, Spherize, Twirl, or ZigZag distort filters on an image they are dimmed (unavailable).

Solution: Reduce the pixel dimensions of the image.

    There are maximum image pixel dimensions for each of these filters:
        ZigZag:     8000 x 8000
        Pinch:      11500 x 11500
        Spherize: 11500 x 11500
        Twirl:       11500 x 11500