Lighting update failure

I’ve got an issue in that each time I rebuild lighting there are a group of lights in a room that won’t update.

I have to select and then deselect “affects world” in their properties for them to work, now this was a minor issue, but now what’s happening is if I do this (select/deselect) there’s a character in an adjacent room that becomes pitch black and requires rebuild to sort out.

This is a bit of a strange cycle as I can’t light the character without rebuilding the lighting, but every time I do rebuild, the lighting in this room goes dark and if I do the select/deselect lightings fine but the character goes dark and so on and so on.

What the heck is wrong with my map, there is no link between the lighting or the character, except that they are in adjacent rooms.

I’m using 4.12.5 I’m thinking could this be resolved by moving the project to 4.15 as it could be an editor version problem?!

Please help I’m tearing hair out!!!