Okay, figured it out. I don't have a real dummy load, but a BNC terminator with 50 Ohm. This one is rated for only 0.5W, which I used as PWR setting. The SWR bargraph (while TUNE is active) start to appear when I use a TX power of 0.4W ... 0.5W. However, the SWR display (e.g. "6.6-1") in the VFOA display only appears above 0.7 .. 0.9W PWR setting.