An integration can be triggered in several ways. If a trigger fails, no errors are shown in the Connectivity studio Integration operations history.
Batch job
You can run a project, message or web service in batch, usually in recurring mode.
If the message or web service does not run at all, the
batch server can be down.
Custom code
You can run a message from custom code.
If you use custom code to run a message, and the message does not run, probably, the custom code is not right. You need a developer to check and repair the custom code.
See also