Why did the parvos sister candidate not spawn after I completed granum void challenge?

I put in a zenith granum crown and completed the 75 kills challenge, Unfortunately when I got out a sister candidate did not spawn.

So I completed the mission ans tried again yielding the same results, can someone tell me if I've done something wrong?

Edit: after further investigation I have a lich active that I didn't notice was active. Thank you everyone.