In the image you can see I can't enter Stockholm territory because this CS is Angry with me. Bribing it to Normal doesn't grant access neither. You need to bribe it to Friends state to freely enter its lands. The CS is allied with Persia and I have no open borders with them. Anyway, I've made the test to bribe open borders with Persia and also I can't enter the CS tile. I've also attached the savegame.