The DLP clients appear as offline, even if they are online. This happens after a power failure or after restarting the DLP management server.
Restarting the agent services resolves this issue for a day, and then all the clients will be disconnected again.
When clients who are marked offline save an existing or modified file to a local network share, the offline rules force a prompt for justification. If they click Cancel on the justification prompt, the file is either completely deleted or the contents get deleted and 0K file is created instead. All data on the file is completely lost.
This issue is caused by a bug on the Linux kernel creating a time jump. It happens on the DLP servers running as virtual machines with multi-core CPU.
To resolve this, use a single core CPU virtual image.