Indicator lights disappears
I have "little" problem. I made indicator lights to my map and then I add doors and button to other place. when I zoom out to see the whole map I saw that almost all of my indicator lights has disappear. That happens me twice. Watch the picture and you'll understand (if you can't understand my english 
) Can I restore them to come visibly or must I do all work again?? 
I'm not sure what is causing this issue. The first thing I would check is the "Brush Faces" property in the overlay. Clear out any value(s) in that field, click the little icon that looks like an eye-dropper and select the brush face you want to use, in this case the floor. Also hit ctrl+p (I believe) to check for problems. If an overlay is trying to use the "angles" property this can cause problems but the "Fix all of this type" button can solve it for you.
Looks like you drastically changed the floor brush (clipping, recreating). Do what bizob said and you should be good.
It is alt+p. I use it a lot. I really do not think that can help you, I've never really tried that solution for this problem. I always get "angles" error, with out them diapering.
The more you give, the less appreciated it will be received.
Well, are you creating new info_overlays, or simply copy and pasting them?
I ask this because, like previously said, if you copy&paste them, they don't update what brush face to plop the overlay onto. You need to:
a)Don't be lazy, and just make new ones.
b)Go into the properties of all the ones that wont show up, make sure that the correct texture is selected, that the correct brush face is selected, then see.
Hope this helps, it's late here >.<
That brush face think worked thank you. 
ps. I'M lazy 