A hidden failure is not obvious under normal circumstances. Hidden failures can expose your facility to increased risks that may have serious consequences. The sources within your facility for hidden failures may be many. A good reliability program will give special consideration to these types of potential failures and their associated risks.
Have you considered that the software used within your facility may lead to hidden failures in a sense? Your software may lack documentation, reporting, and analytical capabilities. Data may be hidden, improper diagnostics made, or corrective action not taken based upon the information, etc., all of which can lead to equipment failures. Intentional misuse of the information may be possible as well without the ability to apply proper oversight.
Make sure the software you use properly collects, stores and reports information of value that can be used to drive your maintenance and reliability efforts. Make sure that the information is correctly analyzed and appropriate action is taken. Otherwise, your software tools may give you indications of problems that go unmitigated until costly failures occur.