After a long break from mapping i decided to try and get back into again, to help refresh myself with everything i decided to recreate the Kabul City ruins map from MoH. Now everything has been going fine, progress has been great and all looks good, until recently. I began the stage of heavy detailing this week, adding decals and more models/prefabs to the map to "fill it out" and look more realistic, however, i now have an issue with all the stock models and prefabs having a multi coloured look to them.
I have got reflection probes and the light grid is added, there are no leaks in the skybox and error logs only show problems with some repeated textures (large buildings with plain sides that are only partially visible) and floating textures ( more than likely from adding decals to walls) so im not sure where the problem has occured, i dont have an older version of the map saved so cant roll back and redo the work, anyone got any ideas/suggestions???

2 screenshots attached, one before detailing started and looking normal, and one of how it is now

This will be caused by either a missing lightgrid, missing reflection probe or leak. Please post your full compile log.

Ok cheers mystic, i'll look into that, would love to post the compile log but i can never copy it all before the command prompt box closes and im pretty sure something crops up when it compiles the light.

As said by Mystic its a lightgrid problem, see HERE

Well i have a light grid and as far as i could tell it was fine, now, funnily enough this has just happened on a little ffa map i was working on, and incidently it happened after i placed a light entity that was coloured. This happened in the first map after placing a coloured light entity so i'm not sure whats going on now as both light grids were done so could it be a problem with the settings for the light entity?

Probably the lightgrid information had changed after you added new lights and other things in your map. That is why I don't bother with lightgrid until the map is finished.