Hello

I recently installed a brand new moen banbury tub and shower combo.
I used pex piping and tested all connection for leaks and to verify everything was functioning before putting up our tile backer board as well as the tile.

When I was testing everything, I ran a copper pipe out the wall and turned on the taps. Hot and cold worked great and when I placed my thunb over the end of the pipe, the shower kicked in like it should. I tried both the cold and hot to make sure there were no issues with the valve.

Lastnight I decided to turn on the tap for the bathub (since all tiling is done). I had placed all fixtures on and when I turned on the water, I had some water continuously come out my shower head and tap at the same time.

I removed the tap fixture immediately so that only the copper pipe was sticking out the wall with the end completely open. Turned on the tap again and water still comes out both the pipe(tap) and shower head at the same time.

When I turn the handle completely open on the hot sid(left) the water stops coming out the shower. I don't know why it is not working now and it worked when I tested it, the lines were completely connected the entire time.

How do i fix this?

I went online and found numerous situations
1. Don't use pex from the valve to the tap outlet
2. Distance of shower from valve (this is not the problem as the spacing is 50")
3.Something blocking the pipe (not sure what, as everything has been removed and I even took a metal coat hanger and tried see if it caught on anything on the inside of the pipe)

The problem is that everything is finished and I can't rip out the tile to replace the pex with copper