I was looking for the supply and return from the boiler. But yes, the flow should be away from the mixing valve. The valve next to the mixing valve should be open to allow the cooler, allready mixed water to flow back to the boiler. I don't see the path.
This sounds like a flow problem to me as well. I've worked on a couple of radiant problem jobs, and one thing yo can do is close the return valve, leave the supply valve open and open the drain valve to see how long it takes to get hot water thru the system.
With 180* going out and 80* coming back you should be able the feel the floor with your hand and find the choke point. If the entire floor is cool I'd think it'd be something running bassackwards...
Well thanks to everyone here I think I've got the biggest problems solved. The circ pump was def feeding opposite than it should be. I took the pump off and checked to make sure the propeller was working and not jammed up. I then rotated it 180* so the pump is now feeding the 1" Pex and coming back in the 1/2" Pex. I turned 3 of the 4 returns off and bled the system till I got warm water back out. I still need to replace the mixing valve but hopefully my garage/ apartment won't freeze up and break pipes again. Thanks again everyone