Fragnets response to our ticket there:
Thank you for inquiring us! While I understand your frustration and your need for this log file, we are unfortunately not in control of re-sets and features that might have been induced through game patches, whereas this might be a game server-related bug, causing the log file to get re-set. Are you able to inquiry the DayZ development team concerning this issue instead, to potentially have this issue resolved within the coming weeks? For your convenience, I have attached a link to their contact page for you, below:
https://feedback.dayz.com/my_view_page.php
We remain at your disposal if you have more questions!
Best Regards,