I’ve loaded a netlist into PCBNEW-nightly and the ratsnest doesn’t appear. I’ve enabled/disabled ratnest globally and for selected components and also changed the ratsnest color/opacity. No change. I’ve also loaded the netlist into PCBNEW 5.1.7 and it does appear.
I checked the KiCad bug list and nothing about this problem is reported. Also no pertinent reports in this forum. Something this blatant would probably have been mentioned, so maybe it’s a cockpit error on my part?
This is another recent post in which apparently a part of the netlist / ratsnest is missing. But the post was by an inexperienced user and maybe it was something else.
How do you “load a netlist into PCBNEW-nightly”? From your way of writing it seems you do not use Eeschema / Tools / Update PCB from Schematic [F8] but are using the old / deprecated way of first generating a netlist file.