On the Active Console, the data cells will show a status icon if database logging is enabled.
If the dataview is rapidly changing, it is possible that when certain items are logged to the database, the items may have been removed already. The Gateway would then be unable to locate the XPaths and return the error message.
There is a separate article with subject: Gateway database logging, performance and .dat dump files. Users can follow the suggestions to fine tune database logging, which may help resolve the issue.
Users can check out the Gateway Data Quality Guide on monitoring "maximum data age" to investigate whether a Gateway is overloaded.