dropbox is a good free sight to do so.
Before you try that, Is the offending object that is having light cast through it a plane? I’ve been playing around with the lighting and if you have a plane with a only one side displaying the material, if there is a light behind that mesh it will not recognize it since there is no material for it reflect off of. You can adjust the settings in two places for this. In the mesh details panel you can select “Cast Shadow as Two Sided” or in the material editor properties you can check to have the material be “two sided.”
This may solve your issue. if it does please post back here for confirmation. If you’re still having the problem I’ll gladly see if there is something I can see in your project.
Thank you!
Tim