Cron作业正在运行,但不会覆盖文件

I have the following set as a cron job:

*/1 * * * * /usr/bin/php /var/www/html/recalls/php/savesjson.php

I checked the status and I get this back.

Mar 10 16:29:01 big-hoster CRON[30417]: (root) CMD (/usr/bin/php /var/www/html/recalls/php/savesjson.php)
Mar 10 16:29:02 big-hoster CRON[30416]: pam_unix(cron:session): session closed for user root

The savesjson.php file should execute and basically save a new JSON file (current.json) in the same directory. If I just run this file (by going to the URL), it works perfectly. However, my cron isn't actually updating the current.json file.

current.json has permissions as follows:

-rwxr--r-- 1 root root 0 Mar 10 16:17 /var/www/html/recalls/php/current.json

savesjson.php has permissions as follows:

-rwxr-xr-x 1 www-data www-data 213 Mar  8 14:11 /var/www/html/recalls/php/savesjson.php

What am I missing here?

UPDATE: If I try to execute from the CLI, like so:

# /usr/bin/php /var/www/html/recalls/php/savesjson.php

It appears to execute, but the script doesn't do what it's supposed to (create new file) and there are no errors in my PHP logs. However, the PHP does work if I go directly to the URL (example.com/php/savesjson.php).