BigIP LTM Pool Monitors Stuck on "Checking"

Don't know if this will help, but I had a similar issue with the can't find monitor rule log message after trying to do a sync, and Syed Nazir mentioned to try:

Try the following to correct the issue:

1. Reloaded the configuration by executing command:

   tmsh load sys config

2. If the issue is not resoloved, restart the tmm by executing command:

   bigstart restart tmm

3. If the issue is still not resoloved, reboot the F5 should resolve the issue.