First off, double-check your /etc/sysstat/sysstat file. Ensure that the INTERVAL parameter is actually set to 2.

Next, make sure your cron job in /etc/default/sysstat looks like this:

*/2 * * * * root command -v debian-sa1 > /dev/null && debian-sa1 1 1

After making these changes, did you restart both the sysstat service and the cron service? Use the following commands:

sudo service sysstat restart
sudo systemctl restart cron

Also, verify the permissions on the cron job. The debian-sa1 script needs to be executable. Lastly, check the logs for any errors. You can find these in /var/log/syslog or by running journalctl -u cron.