Can't move from someone else territory

[Hitzuul]

So my army were waiting in a city(not a territory) while they were waiting a player started his game at that village, now my army that was located there can't move or conquer the city, even another on my army can't conquer it.

[Gabriel]

I'm looking into this.

[Gabriel]

You can actually go back from where you came to that city (south).
And the city is the vassal of your own vassal, as such you cannot conquer him (that would be stealing a vassal from your own vassal). That's why attacking this capital is not allowed.

The error message was not very helpful in that context... Also, the fact that your own vassal has a blank name adds to the confusion.

[Hitzuul]

But I came from the north...

[Gabriel]

You cam from the north, but you sent your general south at 3:46 PM yesterday before changing your mind 30 sec later, sending it back to the city. The game thus assumes you came from the south.
It is usually not a problem, as your rights to walk through a territory does not change often while your army is directly on it, but I should definitely make this information available in the UI in some way. I'm just not sure HOW to display such information.

[Hitzuul]

Oh I understand... Yeah it's a pretty specific things to warn people about.