Wierd CUDA graph while rendering in task manager

Hi, I noticed that sometimes is my render going like this, what should be the issue? That it is dropping from 100 to 0% ? I´am rendering with OptiX on nvidia GeForce RTX 2070S.I noticed that it depends on scene, but haven´t figured exactly what it´s causing. Have you ever had similiar issue and how did you fixed it? thanks a lot!