Pixelmator

Cloning in Pixelmator appears to be a problem. Tried it the other day; didn't work. Bought the latest "Pro" version and tried again. Super! Got a job done!
Today, tried with another little job and NO LUCK. Looked on-line and see that it might be an ongoing problem but no real help there at all.
Help with this would be appreciated.
Thanks!
Dick

Just decided to try Safari again … typed in "pixelmator - how to clone in version 3.9"
That brought up, as first listing, https://www.pixelmator.com/mac/tutorials/ios/
One or two comments there had me going back to my project, and that made me realize that I had not been using the just-bought Pro version.
Once that was activated, the Clone tool still did not work.
After looking around in the full-screen window, I saw - up in the left-top corner - a "Layers" option with two choices.
(A 27" screen *does* have disadvantages!)
After clicking on the "Background" layer, the Clone tool worked as expected !
Job done!
Nice to see that Pixelmator Pro can be accessed in Photos by choosing the triple-dots, top right corner of the Photos window.
Dick