canvasdatacli Grab only returns requests table files

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I'm trying to retrieve all of the tables at dates in the past to get a consistent picture for that date.   So I ran a list command to identify the datadump id and then ran a grab for selected data dumps. 

What I'm finding is that very old data dumps now only have requests files.  I did find all 93 tables in some recent datadumps.  Is this by design ?