I usually have soft factor set to supplies and I assumed it is here, but I'll have to double check next turn that Atatack hasnt changed it in his turn which I believe then changes it for both players. But certainly that fits the picture last time I specifically checked the Intel on soviet supplies down south.
As to how supplies are so good in stalingrad, not sure definitively but I've tried to do the right thing overall with the supply priority across the front, the whole rail network is repaired now so lots of multiple lines going east in parallel in the south, and none are railing troops. Combat in the sector was quiet for months allowing supplies in units to fill completely and while no depots built up stores there are 2 rail lines and multiple depots on 4 that seem to flow OK right now. Plus as supplies ok in the caucasus are OK so the Ju52s are sending maybe 300+ extra to the stalingrad sector each week now which helps a little. So yes the supplies look OK here. I can credit loki in general but no private lessons, just from public info
As to NSS in the south, I must admit I thought /assumed there was one down in Azerbaijan representing LL from Persia but maybe that's not the case from revisiting TBD manual. In which case maybe it is coming across the Caspian in which case that doesn't seem ideal for the Reds right now.