Symptoms
When you use columnstore indexes and run versioned scans (SI or RCSI) in Microsoft SQL Server 2019 or 2017, you notice that the wrong result are returned if a tuple mover merge or an alter index reorganization is running on the same table for a Compressed Rowgroup that has a 0 row count.
Resolution
This problem is fixed in the following cumulative updates for SQL Server:
Each new cumulative update for SQL Server contains all the hotfixes and security fixes that were in the previous build. We recommend that you install the latest build for your version of SQL Server:
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
References
Learn about the terminology that Microsoft uses to describe software updates.