I'm having the same problem. Good cold and hot water supply, but the hot is gone. Cold works fine. In my case I can loosen the cartridge (turn the cold off first) and still no hot comes out. So, it is plugged in the main body of the faucet below the cartridge. One trick I read elsewhere might work for you but didn't for me.
With everything assembled, turn off the hot water supply and disconnect the hot water feed line from the faucet inlet. Leave the cold water connected. Put a bucket under the open end of the faucet's hot water inlet. Turn on the faucet and set it in the middle or a little towards hot and put your finger over the spigot end blocking the outflow. This will force the cold water backwards down the hot inlet and perhaps dislodge and flush what is plugging it up.
Worth a try. My facuet's part guide doesn't show how that inlets are contructed inside the main body of the faucet and I can't quite figure how it comes apart. I couldn't seal the end of the spigot well enough to generate much backflow. Tomorrow I'm going to use my compressor to try to blow harder back thought the hot water hole inside the faucet body. I probed it with a wire as well. If this fails, I'll call Price Fister and take advantage of the lifetime warranty.
Bill