I was exploring the border of a neighbours territory with my Sovereign when the neighbours terroitory expanded.  I couldn't move without declaring war so attempted diplomacy instead. (Consider this problem A - stranded sovereign)

First off I hadn't research the treaty to allow movement in enemy land, so I waited and did that.  Once I had it, I still had no option to sign the treaty so attempted to trade technology so that the neighbour would have it too.  Only one problem, he would not accept any offer I made, no matter how much of my technology I offered him, even for free.  So either diplomacy is broken or I really suck at it.