This is a bug in EG 4.2, but has been fixed in EG 4.3. It only occurs when opening the data after an attempted open on the data has already failed at least once during that session (one scenario: someone else had the data open in update mode the first time you tried to open). If you encounter the issue, you can workaround it by saving, closing, then reopening your project or by removing the data element from your project/process flow, then readding and reopening the data.