I had a rather hard time on adding the PSU to the layout. The Diagnostic mode in the app wasn’t available/working. After I struggled more than 3 hours (including hard resetting the lines, wifi network, uninstalling the app, etc.), I ended up unmounting the entire layout and reinstalling it, connecting the PSU at the 18th line. At first it didn’t work, however, after another few attempts, it turned out well. A week after, miraculously, the app warned me about the wrong placement of the PSU and indicated the correct position. Now everything works fine. I hope in the future Nanoleaf will improve their app and post video tutorials on how it should be done properly. Btw, the help section is a disaster.