Update - I had to rebook the machine again and the problem cleared up.
I could not run the old Pixlemator either, however problem solved.
Last night my Macbook Pro 2019 15" updated to Mojave IOS 10.14.6 (18G87)
Now Pixelmator Pro does not work
When I click on it the mac wheel spins and nothing ever appears.
It shows up in the doc as if it's running, but it never appears.
What other info do you need from me?
Is something not working like it should? Let us know.