No output_log.txt in batchmode after upgrading to 2018.3.9??

I put multiplayer down for a while, during which I upgraded to 2018.3.9. Now I'm back to working on muliplayer and trying to test my latest build, but running in -batchmode -nographics no longer produces an output_log.txt for me to see what's going on?? Running the same exe as normal produces the log file as expected. I am not applying any further command line argument other than -batchmode and -nographics. ?? Pretty much stopped dead in my tracks without a log =[