CK III - Gifting duchy and county to unlanded son causes him to become independent

[Lawlcat]

Short summary of your issue Gifting duchy and county to unlanded son causes him to become independent

Game Version 1.0.3(935c)

What OS are you playing on?
Windows

What platform are you using?
Steam

Do you have mods enabled? No

Have you tried verifying your game files (Steam only)?
Yes

How much "pain" is this causing you?
7

Please explain the issue you experienced in the most condensed way possible
I am the emperor of Scandanavia with a large realm. I usurped the Jarldome of Strathclyde and granted it, along with the Earldom of Livs, to my unlanded third son. The pop-up box indicated he would become my vassal, and after gifting, the on-screen toast message claimed he became my vassal, but he was now an independent ruler.

Please explain how to reproduce the issue
From the attached save game, usurp the Jarldome of Srathclyde, and then gift it and the Earldome of Livs to Prince Fed Aslaugsson

Is there anything else you think could help us identify/replicate the issue?
I have uploaded a video of the issue occuring

and have also attached the save file that is 100% reproducible

I have attached a save game
Yes

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