Look at the pump. Water still goes through it. Might be two lines one to hot water and one for cold water side.
Pump might have more pressure and force it to the faucet. Unscrew the aerator and see if it comes out. Might have to take the valve out at that water point.
There is an obstruction, in the cold water side, pipes, since you took off the filter. If you can squeeze the pex pipes you might giggle it down stream whatever it is and then maybe not.
Any RV Plumbers here?
Just for the heck ,of it check the fill valve selector. It would seem both sides would be affected if it was only partially in position.