Advanced Agents disable themselves if an Exception occurs that is not handled.
A stack trace will be generated. Look at SMA -> Agents.
My guess is that your Advanced Agent either completely lacks error checking or is not checking for errors at the step where the error is occurring.
Advanced Agent Activites should be written like Java methods, i.e., try + catch + finally.
Check for errors in Advanced Agent Activities liberally. When an error is detected jump to a "catch" step that executes Log-Message + stack trace. For the message itself output context information followed by the function: getWorstMessage(tools).
Usually a stack trace indicates on what step an Exception is thrown. Isn't the Exception's stack trace visible in the logs?