Killed uber lilith for the first time on 6/1/2024, did not receive a spark.
I had the same issue, defeated her for the first time this season today and no spark.
I would also like to report this too. I just defeated Uber Lilith within the last hour (6/2/204) with my brother (Limbo#12859) . I’m on PC he was on PS5. Neither of us got the spark.