Here's what I think is going on:
Line 9 reads Globals.G.MinAsteroidSeparation=1250, this is a tricky one to understand.. basically when asteroids are created, if they are too close together, the game moves them apart unless the .moveable = false is applied to them. This moving apart means that in some procedurally generated games, the randomly generated asteroids squash each other apart such that the paths between them become different. So in some cases a path for sending seedlings between two asteroids that was available in one game, will not be available in the next game.
Line 17 reads Globals.Asteroids.MaxTrees=0 which means any procedurally generated asteroids will naturally have a maximum of Zero trees.
Line 48 reads AddAsteroidRing(4, -100, 100, 800, 150) which adds a procedurally generated asteroid ring containing 4 asteroids, clustered around the centre. In some cases, the player's asteroid will have a radius of 610, so because the seperation distance is so large the chances of these being squashed outward a long way become high.
Line 51 reads AddAsteroidRing(10, 0, 0, 3400, 250) which adds a ring of 10 asteroids centred on coordinates 0,0. The distance of the ring from the centre point is 3400, which means some of the asteroids may wind up in the 3400,0 region, putting them roughly where the asteroid in the screenshot appears. Because they are procedurally generated, all 10 of these asteroids will by default have a maximum of Zero trees, and the game will be free to move them about.
I propose that the game has created the player asteroid and all the inner asteroids to have extremely large radius's. This meant that the asteroids in the centre were squished outward by the minimum seperation rule until they actually bulge past the asteroids created in lines 53 - 111, and push against the OUTER ring of asteroids created on line 51. This pushed a zero tree asteroid out so far that the only route to it became via another zero tree asteroid. This unlikely scenario creates the rare problem described by the original poster.
To fix, my suggestion would be to reduce the maximum seperation distance a bit. :>