I took Delin's lands in the last game. Killed everyone there and visited all the green spots (the green chest icons?). Not sure if that triggered anything but the green border dissapeared and I could build there.

Might not work for all zones, but at least the ruins of the empire wildland, there was one tile that had a bit of a golden glow (and I believe a statue/ fountain looking thing), and that was the only one which I could settle on, which then unlocked the rest of it to become neutral (unclaimed) land.  So see if there's a special looking tile perhaps?

Ya, I had the same issues as you in the fight. Ranged weapons and magic both can't be used because they count as "blocked" from view or something. The only cool thing for me was that I got some sort of eye loot from the boss which let me select a city to put the "trophy" of my victory in. It added growth, plus strength to defenders, so it was pretty nice. Borders are still green though. I'm having a similar issue with the firelands one. I had a weird bug where the pyre of man duded had too many guys in his army, so he didn't show up when I attacked his stack. However when I killed his troops the battle ended and it counted like I had beaten him (in the battle report it showed I killed him). His stack counted as "Epic" and all my champions ended up leveling up like 3 time lol. Firelands won't go away either though.

I killed off the earth elemental lord the other night as well, visited all the marked locations, and nothing happened (and the quest to clear it was still there), but when I reloaded my game the quest was gone, and the green borders disappeared.

Bizarre issue with the Mist/Shroud(?) wildland too. I conquered the city and my first city disappeared without a trace. The border was still green and all I got was this lame empty city who's only difference seems to be that it has no border for me + darkling militia(which is weaker than normal kind:P).

I'm staying away from wildlands until Thurs, they break every game I play

For the lava area there were two green (treasure icon) stone circle things, taking both of them gave me no items but once I hit the second one the green area disappeared and I could build an outpost in there. This was after I killed the boss, which I didn't actually kill he just auto-died because his stack was too large to fit into the battle and he wasn't one of the ones that showed up in the fight.

That was the only wildlands I've found so far.

Got the Titan battlefield to disappear and build after killing everyone, but the Winter one did not die no matter what... I even had all the world under my influence, so no monster could have escaped...

Worse yet, there was a third one, that was basically a circular mountain range with a gate, and what seems to be a city in it's walls, and a dragon mounting dude in the middle, all this I know because I managed to get someone with high sight to find it out, as I never got an intro of it, nor the gate ever opened (I could not click near that area)

I just had the Ice Wildland bug on me. I killed the huge elemental (who needs the ability to crush trees when he moves so that he doesn't get stuck and killed the way I did (i feel lame). But i did this before I actually went in the wildlands, so it gave me the quest AFTER I killed him... so no good options to fix the problem.

So in the earth wildland, when I got in combat with the Elemental snake overlord, the game froze.

and nothing happened. 

i realize that I meant that rather than say it was not responding it simply sat their, waiting for the elemental lord to go... but he wouldn't