Want to ask this as i am getting closer to this mission and noticed that the lparchive said that this mission is broken somehow, like the only tunnel to underground doesn't work which is essential to beating this mission called Moon for ED in the moon project add-on.

Edit: I did just beat it, the tunnel was working and i could finish the game with ED the last faction i needed to beat it.

we've recently been dicussing this at InsideEARTH, it seems the bug is random from what we can tell.

Discord

What I found when playing this level on the Hard difficulty is that the entrance is blocked by a mine. In my experience, if you order a unit to take the Tunnel Entrance while that mine is still there, then after the mine destroys the unit, the Entrance gets permanently glitched out and ceases to function.

To avoid this problem, move a unit onto that mine deliberately to destroy the mine, sacrificing the unit. Now the way to the Entrance is free, and you can safely use it without glitching it out.

I'm also running into this problem. By using cheats I found that there are a few Craters with rocket launchers near the tunnel entrance, and they attack it, even though it's supposed to be neutral, so by the time I get there it's already destroyed.

Edit: it is also possible to cheat to add in a Gruz and build a replacement tunnel entrance. This is the minimal cheat necessary to beat the mission if you otherwise play honestly:
newone 100,30 edubu1
moneyfornothing 1000