Turn the lna gain up to maximum. My settings are this - Im still on 1.1.4 on my live system as I couldnt get 1.2 to install correctly when I tried last weekend
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Set your sample rate to something like 2.048Msps & click start To make the fft visible. You may need to adjust the fft max & min too get a sensible display. Where you need to set it to will depend on your local noise floor.
ALso make sure you have the right dongle selected - mine works on
Generic RTL2832u OEM (although its a few years old now)