Keep in mind that the information reported by Dynatrace at DB level is based on queries triggered by the Application monitored, on the application server side. What this means is that Dynatrace will place some sensors at JDBC, ADO.NET... frameworks to report response time and number of queires. If this calls have a problem, should trigger an exception, and this exception (if using standard frameworks) should be captured by OneAgent.
So my recommendation is to double check those invocations that you identify as failures. Review the purepaths that contain that kind of queries and check if there is any exception thrown. If you find any special exception but it is not counted by Dynatrace as failure, you can modify the Error Detection > Custom Handled exceptions or Custome errors, to count those inserts with some specific behaviour as errors.