I will hazard a guess that this is the short story "What Continues, What Fails" by David Brin"What Continues, What Fails" (1991) by David Brin. It's not a perfect match -- the female protagonist is part of a research team that is observing collisions of micro-black holes with a bigger one in order to observe things inside the bigger one, vs. waiting for one to collapse -- but the theme of universes spawning black holes which yield similar universes is a major focus.
Instants after the nought's formation, inflation had turned it into a
macrocosm. A fiery ball of plasma exploding in its own context, inain a
reference frame whose dimensions were all perpendicular to those Isola
knew. Within that frame, a wheel of time marked out events, just as it
did in Isola's universe -- only vastly speeded up from her point of
view.
Energy -- or something like what she'd been taught to call "energy" --
drove the expansion, and traded forms with substances that might
vaguely be called "matter." Forces crudely akin to electromagnetism
and gravity contested over nascent particles that in coarse ways
resembled quarks and leptons. Larger concatenations tried awkwardly to
form.
But there was no rhythm, no symmetry. The untuned orchestra could not
decide what score to play. There was no melody.
In the speeded-up reference frame of the construct-cosmos, her
sampling probe had caught evolution of a coarse kind. Like a
pseudo-life fabrication too long out of the vat, the universe Isola
had set out to create lurched toward dissipation. The snapshot showed
no heavy elements, no stars, no possibility of self-awareness. How
could there be? All the rules were wrong.