She didn't lose sight of him. She saw him clearly move around the corner, and he didn't come out. Maybe there was a door there that she hadn't seen and he'd gone inside of the building? That would make tracking awkward. She'd have to wait until the sound of footsteps retreated before slipping in after him. She didn't hear a door squeak or footsteps now. She did smell him clearly and she could hear his heartbeat. It wasn't hard when she managed to tune out the din of the city.
He was waiting.
Not bothering to quiet her steps any further, he'd be able to hear her approaching him. She walked right past where he hid himself, without bothering to turn around. It was a big risk, but he hadn't shot her the last time.