Basically my setup is this:
RPi HDMI -> 50cm HDMI extension lead -> StarTech HDMI-VGA converter* -> VGA cable to monitor.
Unfortunately there is no display when the extension lead is there. Without it, everything works as expected but when extension is present the monitor doesn't even wake up. I've tried booting in safe mode, changed the config file to include hdmi_force_hotplug=1 and tried varying config_hdmi_boost values (I've tried between 4 and 10). I've also tried using a couple of different monitors as well as putting in the extension after booting without it. Unfortunately nothing seems to work and the monitor goes to sleep.