Hey,
I am on OSX 10.13.6 and Unity 2018.3 with PM 1.9.0.p16
I have one project with a previous PM Build because i did not update PM in that version and it works just fine, its just the new projects i am creating with the new PM Version causing this issue.
No, I have a macbook pro, i did not update Unity only PM.
I tried resizing the pm editor window as well but it did not fix the issue.