Slider + touch works and visualises as intended, only the visualisation of single slider in control mode is affected.
Out of interest I went back to the old firmware still available on the website updater, and with the old firmware the visualisation of control mode with single slider works as it should with no flickering, the same way as in record mode.
Now I updated back to the newest firmware and the flickering returned, same as before. Are you sure this is not a bug in the newer firmware? Or is my unit working differently for some reason?