Take a look at the doc I linked above. For Precomputed Visibility to work, the camera (whether it’s the one used while working in the viewport or the one attached to your player must be within that cell. If it’s not, there is no culling with Precomputed Visibility.
The character being in or out of the cell doesn’t matter. The camera position does. You need to adjust the playareaheight in this case. That’s covered in the link as well.