I'm a softball ump, but this is all the same stuff here.
Do you get paid by the school, or the assignor? All sports around here get administered by BOCES, which is a county wide purchasing co-op, they run the trades education, etc. They have an athletic coordinator's office who schedules games, schedules officials, etc. And all sports contracts are negotiated as one. VERY rarely do we have any problems, so when I had exactly this about the same time, I knew I was going to get paid. (we get a paysheet after every month that we sign and submit....and wait two weeks to get paid
)
They took over the paying to forstall just kind of this thing, as I am assuming the schools have already paid into a fund. When I started many, many years ago, we got paid by individual schools - and THAT was a PITA......