We had a very unusual situation at work. Giving a bit of context first, the setup is: we have a Java application, using Spring Boot and Hibernate, connected to an Oracle RAC database.
We added an item to one of the database tables using that application. We could SELECT this object, and we could UPDATE it... but only for a couple of minutes. Then it simply vanished.
We though it could have been removed by someone, but according to the DBA logs, there wasn't any INSERT in that table during that whole day; although, the person which added the item happened to be recording her screen, so we know for sure that it happened, and when it happened.
How could this situation happen? There were no errors in the application logs indicating that there could have been an error during commit. And during the times we updated the item, it had to be listed first, using a SELECT.
Also, we never had a situation like that one before, and we have been using that same database, and that same application, together, for over a year.
In case I missed any relevant details, just ask.