When adding a class in creator, there used to be a dialogue informing about the inability to add the new files to cmake. it then offered to copy their file paths and open the cmake file.

I think it is a new option to remember that decision (so no dialogue is opened). Also new (i think) is the option in preferences -> CMake -> Adding File Settings.

I believe, that the labels are in reverse. When i select "Do not copy file paths" it does copy them. When i select "Copy file paths", it only opens the cmake file without copying them.