445 Hydraulics info needed

I have a 2001 JD 445 with Hydraulics up front and a 3PH out back along with the mower deck that works off the Hydraulic system.
A few weeks back I installed a front quick release 4 way plow, closed the valve by the hose hook up and the front plow works great. The rear 3PH would not go up or down which I would understand as being right as I closed the valve to send psi to the front plow assy.

The question I have and that I ran into today is with plow all the way up if I open the valve then try to raise the 3PH the plow also turns. The plow turns and hits the end of travel before the 3PH moves. I thought if the valve is open or closed it seals off 1 system from the other to have them work independently of each other. Am I wrong in thinking this way?
Because I thought when this valve is closed and just the front plow moved not the 3PH, I reopen the valve and both the plow & 3PH move and yes the valve is bottomed out both ways, in & out so what is up?

I did not try this but guessing I could un-hook the hoses for the turning of the plow to see what that does but my thinking is this will let the 3PH work as it did before I installed the plow.

I use the 3PH for pulling my lawn sweeper and the plow to push the leaves where I want them as I cant get the sweeper in that area and why I have both on the tractor at the same time.

Thanks for any insight on this.
Dave ----