At the moment I consider it as a bug in PL 4.3.4: After 4…5 images I use local adjustments, all of a sudden I cannot choose “control points” in the radial menu. Shutting down and restarting PL allows me to select "control points again. Don’t understand the reason and it’s really boring and bothersome.
Are you using MacOS? Maybe it’s related to this bug:
Yes, I’m on Mac-OS. Thank you for your reply. That means, because control lines were only introduced with PL5, they carry a rather big bug with them for more than one year? So, my doubts about upgrading to PL5 grow parallel to the bug’s size… These control points/lines is just one thing DxO likes to brag about. I used them occasionally, yesterday a bit more extensively and soon it proves itself as unreliable. I could use them again after shutting down PL and restarting. But that’s an emergency measure, not workflow.