HELP Please... Final Due tomorrow and building lighting is replacing materials...

The title says it all. Every time I go to build my lighting the engine is replacing all the materials I have added to the walls and such. This is for my final and it is due tomorrow. I am using 4.9 on windows. This just started happening and it is killing me. Any help would be greatly appreciated.


To get help quickly you might want to add a little bit more information. For example: what are they replaced with? Additionally, in cases like this it is often very useful to post a screenshot as that can make finding the cause a lot easier.

If it’s turning black then it’s due to your lightmaps