What do switch between Analoig and Network? This is an option only for input channels, but it has nothing to do with the Monitor section.
I just added a 32R to my SL 16 and set it to Stagebox Mode, connected one stereo headphone amp to outputs 1+2 of the 32R and one stereo headphone amp to the Monitor Outputs of the SL 16, linked flex mixes 1+2 and sent a stereo signal (radio) to linked channels 9+10 (jack inputs). I hear everything everywhere and I don't know what could be a reason making such a basic set-up not working. Honestly, I have no idea.
Maybe you should reset project and scene (separate!), make a Master Reset of Digital Patching and start everything from scratch. It WILL work this way, I am sure. ;-)