I just got my Organelle today and I am having the same issue here. I am trying to connect the Organelle to an older display, that only has VGA input. I am using a HDMI > VGA adapter, but Organelle doesn’t recognise the display. But as soon as I connect Organelle to a HDMI display without the HDMI > VGA adapter it works straight away. But I could only use that display for a quick test, so it would be really nice to be able to use the HDMI > VGA set up. I might have to add that this is one of the cheaper HDMI > VGA converters, that doesnt need power. There are some more expensive ones that needs power too.
I have actually use the same display and same HDMI > VGA cable for my Pi3 and it works fine. So I think it should be possible to get this working in some way.
@oweno, have you tested HDMI > VGA cables for the Organelle?