Do you have the variable nvda_drv 1 defined in your nvram? It seems like the bootarg option is no longer recognised by the web driver. Type sudo nvram nvda_drv=1 in the console and check that the line nvda_drv 1 appears in you nvram (sudo nvram -p) and that it is persistent between boots. boot-args nvda_drv=1 seems like it is being ignored by the web driver.
Hope this helps.
Thanks, I'll check that tomorrow. And yes, I was using it as boot argument. In case it's not in nvram, how exactly should I go from there?