HQ Lightmaps disappear after closing and reopening

Hi,

I built my lightmaps over night using swarm coordinator on 4 machines, and they looked good when finished. So I saved all, closed the unreal and reopened it, and now it is showing very very low quality lightmaps which might be from a test build earlier? I’ve tried disabling texture streaming which didn’t affect it. Has anyone else experienced this or got any ideas?

Thanks
Troy