The HeartTuner – comes up with one screen (for example) like the power spectra – shows NO DATA>. just empty..??
At the top LEFT hand corner of each of the moveable scaleable data display windows – like POWER SPECTRA and COHERENCE and TIME HISTORY, there is a little button to CLICK IT ON AND OFF!! (Switches data into the window). The HeartTuner remembers how the screens were switched last time used, so maybe the window switched off – was a left over from last use. There are 2 issues: one is that the main control menu has switches to show and hide each DATA SCREEN, and SEPARATELY – each data screen has a click button – top left – to switch the data processing inside that screen on and off.