Turns out I must have had some sort of freeze.
Put the truck in a heated shop for a while and they started working again. I pumped all of the fluid out into a bucket and it definitely appeared to be pretty watered down compared to the new bottle of fluid I had. I had the truck serviced right before Christmas. I highly suspect the lube kids topped the reservoir off with water.
Installed some fresh, undiluted fluid and I think I?m good to go.