Mugo Pine Issues

I bought this mugo pint earlier this year, all I have done is repot it.

It is actually two pines that had a twisted and intertwined trunk. What is happening, and I hope the pictures show it well, is that one of the pines is growing well (top section of the picture), pushed some new growth this spring, has strong coloring, etc…the other either did not push any growth or such minimal growth that I did not

even notice, and has a very dull green color and is starting to get brown needles etc.

Any thoughts of what might be causing this. Two plants, same well aerated, efficiently draining container, intertwined trunks that I did not disturb during repotting in traditional 1-1-1 soil mix, and fertilized using a pellet fertilizer with a 4-6-4 chemistry (Uncle Bills, ran out of biogold).

Any thoughts?