First up, SkyRoof is awesome ! Just wanted to get that out of the way.
Secondly, I too can't make it work with the RTL-SDR Blog v4, though my v3 dongle works fine. Delving a bit deeper into it, this seems to be an issue with SoapySDR which has recognized issues with getting the v4 to work. There's a discussion about it
here on the SoapyRTLSDR Github but there doesn't yet seem to be a solution to it.