Symptoms
Assume that you perform an ALTER operation (schema modification or turning system-versioning off) on an in-memory temporal table. In this situation, you may lose some of the historical data that is stored in an internal history table at the moment of query execution.
During that operation, about one million rows will be moved from internal to an on-disk history table.
Resolution
The issue was first fixed in the following cumulative update of SQL Server:
Recommendation: Install the latest cumulative update for SQL Server
Each new cumulative update for SQL Server contains all the hotfixes and all the security fixes that were included with the previous cumulative update. We recommend that you download and install the latest cumulative updates for 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.