That's unfortunate. I don't think a setting is required. I will look into that as well.
I recently successfully completed france 600 AD in 1.17. Did you wait until 10 turns after their spwan? +1 if you want to avoid them spawning additional armies. Scaleable by game speed.Playing as France in a 600AD start, i cannot declare war to Italy.
No option in dipolomatic menu.
No ALT-Click on civ name.
Contacting other civs (for example Poland), it seems possible to ask him to declare war to Italy, but it is red.
Spain, England and HRE already vassalized.
It is about 1300/1400AD
I have that as well, also in previous versions. Not 100% of the time though. It's always a gamblec) For some reason the 'Quit to Menu 'button is causing me to either 'Quit to Desktop' or outright CTD. I'm wondering if this might be related to the above and there's a problem with my install, or if it's some known issue.

Nope, it's in English.Just to rule that reason out, is your game set to a language other than English?