Zone detection is ‘Automatic’ by default (i.e. which will almost always default to ‘WholeBody’) so that would require all character parts to leave the zone before the exited event is fired. If this doesn’t happen, can you DM me please and we can take a look to see if it’s an issue on our end.
If you would like to change the detection from whole-body to just the centre of the HumanoidRootPart, you can do:
zone:setDetection("Centre")
(more info here)