Piwik proxy script only logs visits at hh:58:ss and hh:59:ss (no replies)

Hi,

I have a strange problem when trying to track visitors using the proxy script. The problem does not ocur when tracking visitors using the Javascript code.

My log book only shows a small percentage of the visitors. Furthermore, *all* logged visits are registered at hh:58:ss or hh:59:ss.

Is it possible that some kind of caching is taking place?

Piwik Server:
TurnKey Linux 13.0 / Debian 7.2 Wheezy
Apache2
PHP 5.4.4-14+deb7u11
Piwik 2.4.0-b7 (stable release showed same results)

Website Server:
FreeBSD 8.1-RELEASE
Apache2
PHP 5.4.29
allow_url_fopen: On

Using the proxy script code from github.

All piwik.php requests show up in the website server logs. The piwik server logs only shows requests at hh:58:ss or hh:59:ss.

Help appreciated!