CK III - Other MP players unable to interact with a player

[ZacmanTheDamned]

Short summary of your issue
Other MP players unable to interact with a player

Game Version
Fleur-De-Lis 1.5.0.1

What OS are you playing on?
Windows

What platform are you using?
Steam

What DLC do you have installed?
Royal Court,

Do you have mods enabled?
No

Have you tried verifying your game files (Steam only)?
No

How much "pain" is this causing you?
10

Please explain the issue you experienced in the most condensed way possible
Other two MP Players (Kriwe Chungus of Lithuania and King Karnak of Ruthenia) are unable to use any diplomatic actions with High Chieftain Balongis. Any attempts are blocked due to 'Pending diplomatic request,' however Balongis has no pending requests with either player. Detected when Kriwe Chungus' player attempted to grant Balongis' player (the host/me who is uploading the save) the Kingdom of Poland title (and thus guarunteeing that his entire realm will be ripped apart by succession when he dies)

Please explain how to reproduce the issue
Unknown - unable to identify source of issue. See attached save.

Is there anything else you think could help us identify/replicate the issue?
Player unable to receive the title is the host

I have attached a save game
Yes

Upload Attachment
File(s) attached

 

[ZacmanTheDamned]

Update for this: Have recreated the bug, and this time we're reasonably sure of the cause. I (Maghan Bada of Mali) sent a Betrothal Request to another player (Chief Hogon Fadiga, the Emperor.) He declined (as I'd sent the wrong one), however the game seems to be stuck believing that the betrothal request is still pending. See attached save (And try ignore the catastrophic civil war in the wake of the God-Emperor's death.)