Stir of the swarm bugged ?

Stir of the swarm:

"

Your Maps with Abysses contain an additional Abyss
5% chance on completing Abysses in your Maps for a nearby map to be Overrun by the Abyssal

I'm not sure whether this is bugged or if I am just extremely unlucky.

I allocated this node right at the start of the league when I reached maps. Immediately in the very next map, where I used an Abyss tablet, it procced and I got a neighbouring map overrun by the Abyssal. Since then, it has never triggered again, and I have run a lot of maps by now (I would estimate around 500 maps with Abyss).

The part with the additional Abyss works fine.

I’d be curious whether this has been triggering consistently for anyone else.