When I trigger my "Lock Screen" action, I get a popup menu with three lines in it, all of which say, "Lock Screen". If I click on the first entry it works, but none of the others do. I have double-checked, and I definitely only have one trigger defined with this keystroke. If I change the keystroke to something else, the popup menu goes away, but changing it back to the keystroke I want to use causes it to return.
Looking at the exported .bttpreset file in a text editor, it looks as though there is some junk leftover from when I was testing. Search for "Lock Screen" and you'll see multiple references to running "/usr/bin/say hello". These are actions I deleted, but they still appear in the export file.
Ah there seems to be an issue in the new UI that let's you drag items that already have children into other items that already have children. This will confuse BTT.
That's why your screenshot shows these two triangles:
Ah! I didn't notice the extra children there. I tried deleting them, but that didn't help. I deleted the entire command, recreated it, and that worked.