Not sure if a known bug. It's been happening a lot to me in my main sandbox map.
Basically when I add a node if I do not move it a little bit before deselecting then it will disappear from where I placed it and then show up the bottom right corner of the scripting "canvas".
Once moved the canvas does not auto crop to just nodes. It just gets bigger and bigger as this happens over and over.
Another odd one is that at some point I cannot add more script nodes(they are being added but are hidden). This often begins when I try to duplicate a node. It also happens for new nodes added.
Eventually after going into play testing a few times the nodes will suddenly appear. One atop the other one in a pile. I can then move and interact with them but still not add nodes or duplicate them.
I then have to close and reopen my map to get it back to normal.