That behavior does seem unusual. If you click through to a worksheet, and add a field to the view does any data appear there? Do you notice if there's any difference in behavior if you connect to another data table in the same DB? Or maybe with another DB?
Some data sources will not show a preview, but the data will be there- and that's an expected behavior. I don't believe it's expected for Impala, but it's good to determine if the same behavior occurs with other data sources as a way of trying to figure out if there is an environmental cause.
Thanks for the reply. If I go to a worksheet. There is no dimension or measure fields. All the tables in this data source tend to have the same issue. However other data sources work well. This is weird because several days ago I connected to this data source and things work fine. And I didn't change any settings or environment. Do you have any other ideas? Thanks.