Crimea having almost all diplomatic relations one can have, exept for trade-league/steering, truce and personal union.
Being a junior partner of Castille and Aragon seems to have quite upset the Neapolitan populace, by being to darn confusing. They seek independence from Castille, while having their other overlord Aragon as an ally... who is also a junior partner of Castille.
I also want to take this moment to tell of a bug-encounter, that I could sadly only show if I knew how to create gifs. On two occasions enemy fleets were trapped in the void between the harbor of an occupied province and the sea. They try to leave as they should but they got pulled back before they could enter the sea province, and since you cant fight them while they are docked, these ships become invincible for the duration of the occupation.