I am trying to launch an installer pkg file.
But since I posted, I did other experiments trying to launch a regular app, and I get the same result.
No error, but nothing happens.
I am working with a small test app that simply opens the MAS app. Under High Sierra, it runs flawlessly, under Catalina Beta 19A512f, it simply does nothing.
I just tried to launch the app from a shell with Open, and get the same result. It works as expected under High Sierra, and does nothing under Catalina.
But your post made me wonder if there would be a difference between launching apps, and documents.
To test that, I tried to open a text file. I get a dialog
"test.app" would like to access files in your download folder.
[Don't Allow] [OK]
When I click OK, the text file is opened just fine.
So indeed, launch works for documents, although apparently Apple's paranoia has increased, and the user has to confirm access to the folder.
I am left with the same predicament. I tried to dive into Monkeybread's documentation with a search, but frankly, it exceeds my comprehension.