This post is not on Dynamics AX, but about troubleshooting sharepoint log files.
This morning, I changed the credentials for one of my service "Sharepoint 2010 Tracing Service" to a domain account from the initially set local service account.
The change went successful which means I was able to start the service with the new account. However, the Sharepoint log files were just showing 0 KB. The log entries were not getting populated in the log file.
Had to add the service account to Performance Log Users Group under (Computer Management > Local Users and Groups > Groups)
Please see the blog below for a detailed reference.