I have had similar issues, but you have a couple of years on me.
Yes, the physical therapy did help with my shoulder. But it does take a very long time. I still do it a couple of times a week, years later. Or maybe it was just time, who knows.
Planks bother me too, but you can do for a shorter duration, or do a modified version on your knees.
I have found that using lighter weights or elastic bands and higher reps works best, for me. That and accepting that I am probably too old to get a pro cycling contract or win the world championship.