The first 1000 methods that exceed the method threshold are tracked by default, after which only the external calls are tracked. You can modify this by changing the zpa.additional_buffer directive in the zpa.ini (Linux) or php.ini (Windows).
Default configuration:
In the zpa.ini (Linux) or php.ini (Windows),
zpa.additional_buffer = 0

For example:
If the value of zpa.additional_buffer is 0, it indicates that the first 1000 methods will be tracked; if it is 2, it indicates that the first 1002 methods will be tracked; and if it is 5, it indicates that the first 1005 methods will be tracked.