Why can't I propose a joint war?

[Psychotronics]

I want to ask Trajan, my ally, to go to war with China with me. Joint wars were an option in the past and he joined me against Victoria, but now The option for that deal won't appear on anyone's screens. Any ideas why?

 

[Eagle Pursuit]

He may be allied with the target. Or has recently been at war with the target and has to keep peace for a certain number of turns. Or he just hasn't encountered the target yet.

 

[Psychotronics]

He may be allied with the target. Or has recently been at war with the target and has to keep peace for a certain number of turns. Or he just hasn't encountered the target yet.

He has been at war with them, but it's been over ten turns. Also, can't ask ANY players for a joint war.

 

[Thibaulthc]

Up

Bug still occurring, I can't propose joint wars while they met the other civ, no Alliance, no recent war, they denounced them,... What else might explain it?
Version 1.0.0.129, no mods