I'm not sure about the SIP monitor issue. Your best option might be to open a case with F5 and find out if it's a known issue, been fixed, etc.
You can enable debug on the SIP monitor. The online help shows this for the debug logging:
Debug
Specifies whether the monitor sends error messages and additional information to a log file created and labeled specifically for this monitor. The default is No. You can use the log information to help diagnose and troubleshoot unsuccessful health checks. To view the log entries, see the System >> Logs >> Local Traffic screen.
* No: Specifies that the system does not redirect error messages and additional information related to this monitor.
* Yes: Specifies that the system redirects error messages and additional information to the /var/log/_..log file.
Aaron