We have many threads and posts here on 220 film.
Essentially, the paper and the machines that attach it are the problem.
Ilford's machine wore out, and Kodak's may have as well. They would cost hundreds of thousands of dollars to replace or rehabilitate, and the projected sales made that uneconomic.
In addition, the paper used for the leaders and the trailers is both very expensive and, more importantly, the minimum order required by the paper manufacturer and printer is so large that neither Ilford nor Kodak could justify tying up that much capital, for that long a time, to service a relatively very small market.