I noticed it too, thing is: the black hole had a mass of 100 suns, I had the Sun orbiting it.
The Sun started disintegrating, collecting some of its material back and suddenly it popped into a much bigger size
I checked the mass: more than 2 solar masses...
I continued the simulation, the Sun lost and gained mass up to the point of reaching 35 solar masses, by which time it got swallowed by the black hole. Meanwhile, before the swallowing, the mass of the black hole was still 100 solar masses.