Concealed nodes

[Alisi]

Under what circumstances do they disappear? I'm trying to figure it out. Here we go.

So, yesterday I was mining in Hinter for the Blue O's. I was right at the end of my favor. I finish the second node, saw that a concealed node had popped up, but decided to fly upward because I had just enough time to get one more node killed in the next group of two (the one with the red scrip that always only has 4 in it.) So killed it and a concealed node popped up there too and my favor expired.

I fully mined the concealed node and went back to the last one, and found that it had despawned.

However, just now, I had a concealed node pop up, I mined for the O, and went onto the next group of two. I killed them both and my favor expired, without spawning a new node. When I went back to see if the concealed node from the last group had despawned, I found it hadn't. And then empth nodes don't despawn them at all, despite resetting the normal nodes (though these have been mined for the O.)

So how does this work, outside of mining all the nodes in order? Can only one concealed be up at a time? Or, perhaps, two unmined concealed nodes can't be up at the same time?