I integrated a vassal and now I have an invisible embassy.

[thErgonomic]

I had an embassy in my vassal empire.
I integrated him and now when I check with whom I have and embassy with the game informs me that:
"Has an embassy with the Confederated Kedeshi Colonies, League of Adeex Stars and ."

 

[hrimhari]

I find that withdrawing an re-initiating an embassy with someone else fixes that (say, withdraw your embassy with Kedeshi, and you'll end up with two free embassies, then immediately re-establish the Kedeshi embassy). But yes, I've had this happen (also when having an embassy with a nation that is swallowed up in a war).

 

[PDS-YakAttack]

Hello!
This is a known issue that is fixed in an internal build.
Thanks for reporting!