Hello! Had this exact issue happening twice ( some 6 months ago). There was also no outcome in the respective LS graph (front left one!), blank content.
Moreover, each time the App (and the Audyssey setup in the Avr, when I had not the App) signals out of phase for the front channels, which I ignore consequently.
Btw, Marantz Sr7011 and fronts are Klipsch Cornwall.
Marantz Sr7011, Galactron Mk10b, Pioneer VsxLx50. Klipsch Cornwall, Wharfedale 9.1, Klipsch CP-6. Sony UbpX800, Lg Up970, Hisense 55M5500. 110 inches rolling screen, excelvan cl720d.