I only read the book(s) maybe a couple of years ago. It is about a man who can kind of freeze time in our modern world and step into the frozen area and do stuff but then when he comes out of the frozen time everything he did in the frozen world was not seen. For example, he was chasing someone but lost them in a crowd and he stepped into the frozen world and can spend as much time tracking the person he was chasing by walking all possible routes, when he left this frozen place no time in the real world had passed. Not sure how many books in the series. I thought it was a Brandon Sanderson book but it does not seem to be.
Sounds like Mind Dimensions by Dima Zales. The first book is called "The Thought Readers".
You see, I have a unique ability. I can go outside time into my own personal version of reality—the place I call “the Quiet”—where I can explore my surroundings while the rest of the world stands still.
It could part of the Pathfinder series by Orson Scott Card. Most of the characters have time related abilities and do use them to track individuals.
The description immediately reminded me of The Girl, the Gold Watch, and Everything, by John D. MacDonald (1962). The gimmick time-stopping gizmo is left to a youngster when an eccentric uncle expires...
I'm not recalling sequels by the author, but there were motion picture adaptations.
If you're sure it's by Brandon Sanderson, it could be Snapshot, but that's a bit of a stretch. It's about detectives using a reconstruction of events to find evidence of crimes.
Edit: I haven't read the book, and my comment is based on a summary and the first chapter. Specific elements I can point to include the lack of impact on the world (since he's in a reconstruction), and the opportunity to pursue many leads (because the situation can be run several times). However, the similarities seem to be coincidental.