Layers Disappearing at random
So I am incredibly new to using illustrator (this is only day 2) so maybe this is a stupid question to ask but oh well.
Basically what I am trying to do is take a layer, and put a new layer on top. I then need to trace the bottom layer onto the new layer. I was able to do this yesterday perfectly fine, but today it won't work. Whenever I connect certain lines of the tracing it removes random lines inside the picture (its a building floor plan) so as I am connecting certain pieces it is removing the interior walls, or the cubicle walls at random.
I was able to get most of the outside walls made (I just didn't connect everything) but now as I am trying to do the interior walls things are disappearing as well (the door symbols, other walls, etc.) Which would not matter except it is incredibly difficult to trace when things keep disappearing. I can keep guessing, and a lot of times if I anchor to the piece that disappeared it will reappear slightly (at least the part between the 2 anchors will reappear) but any thoughts or suggestions would be appreciated.
Thanks!

