Agent trace logs are not rolling over per the configured parameters.
If the web server service is restarted, then the logs roll over.
Version: 12.8.x and 12.9 (Applicable to all the supported releases)
Operating System: Windows Server
This can be caused when two agents, using the same ACO, are writing to the same log file.
This can be identified by looking in Resource Monitor (Task Manager > Performance > Resource Monitor > CPU > Associated Handles) and searching for the name of the log file.
When the issue is occurring, the results will look like this:
Two " java.exe " processes with the same PID for the same log file name will be shown.
Create a new ACO and point one of the agents to a new log file.