forever-missing diplomats?

[Caligula]

So ive gotten back into eu4 after some time away from it, and i booted a vanilla game (because mods+new update=no compatability). Ive been doing a Naples game, but ive noticed, when i send a diplomat to spy on the Papal States, they never come back when found out or recalled and i can send another one to spy. When i improve relationships with France, nothing happens asides from me losing a diplomat. When i make peace with any nation, the diplomat just never comes back from the peace deal. Its not even 1500 and ive lost all abilities to do any form of diplomacy due to having no diplomats, and they're all lost forever.

How do i fix this? Can i even fix this? Do i just wait another 6 months to play again and hope they fixed this in some update between then and now?