Why can't I move here?

[Suntechnique]

If the city state is mad at you, it won't let your units in.

That's right. Since one of last patches I wasn't able to enter citystates borders until I get neutral with them after war.

 

[cccv]

I'm neutral with them. 0/30.

 

[ggmoyang]

There is a ghost there. Since it's 1UPT, you can't go there.

 

[wobuffet]

I've been running all around Angry CS's borders in my current game. I don't know what you guys are talking about, Peng Qi and Suntechnique. Nothing in the patch notes ( http://store.steampowered.com/news/?feed=steam_updates&appids=8930 ) indicates there's been any change regarding this behavior.

 

[Pep]

I reported this behaviour as a bug days ago:
http://forums.civfanatics.com/showthread.php?t=436142

If you have time to test the attached savegame, you can verify that you can enter the CS territory only if you ally with them.