CK II - Game crashes after a handful of days following a victory of an imperial reconquest

[K. V. K.]

One line summary of your issue
Game crashes after a handful of days following a victory of an imperial reconquest

Game Version
3.0.1.1 (ONDO)

What expansions do you have installed?

The Reapers Due,
Way of Life,
Charlemagne,
Legacy of Rome,
Holy Fury

Do you have mods enabled?
Yes

Please explain your issue is in as much detail as possible.
Despite having mods, I am sure they cannot be the cause of the bug, because I have completed numerous other imperial reconquest wars with all the mods active, and the game has been going on for about 300 years now. The issue is as follows: as the holder of the Roman Empire, I started a war with the King of Wales, with the Imperial Reconquest CB, for the Duchy of Powys. As the war is about to end (97% warscore in my favour), the king accepts my demands, and I gain the Duke of Powys and his underlings as my vassals. As soon as the war ends, I am able to perform about every game action, including revocation of titles, demand conversion, demand peace from vassals, and others. However, after unpausing, the game proceeds for a variable amount of days (1-4, in my experience), only to suddenly crash. The crash does not happen if I let the war drag on, accept a white peace, or surrender. I'd like to stress the point that none of my other imperial reconquests have caused this issue.

Steps to reproduce the issue.
1: Be the Roman Emperor, ensure there is a (de jure and de facto) King of Wales who has a (de jure and de facto) Duke of Powys as a vassal.
2: Declare war with the imperial reconquest CB for the duchy of Powys.
3: Win the war.
4: Wait a few days.

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[K. V. K.]

FURTHER DETAILS:
It seems that the issue comes from controlling, no matter in what way, some part of Powys. I tried presonally usurping all titles, ending the war inconclusively, and the crash still occurs. More details: Among my active game rules is "No vassal limit", which I am using to keep vassals down to duke level. I thought the issue may have arisen from controlling so many direct vassals, but creating vassal kings had no effect. The crash still happens no matter how many layers of delegation I add.