I turn on directional and I get this
looks kinda cool but not what i’m after
solution (apart from using bakery)?
Hi, can you give a little more information? What version are you on, what are your settings, what is your desired outcome etc? The more info the better 
it’s solved, thanks
reduce scene to 1m=1 unit
switch to cpu render
I also had glowing rectangle artefacts with the GPU lightmapper. Interesting that other people encounter that too:
Progressive GPU Lightmapper preview page-11#post-5399160
I hope the lightmapper team will investigate that.
I have seen cases where this can happen when charts in a lightmap are completely invalid. I.e. they sit inside other geometry, but are still visible. I am looking into fixing this issue. To work around please fix invalid areas in your lightmaps by either adjusting the backface tolerance Unity - Manual: Lightmap Parameters Asset or using double sided GI materials Simple Lit shader | Package Manager UI website