Assume that you rebuild an index with Resumable Online Index Rebuild (ROIR) by using the RESUMABLE = ON option in an instance of SQL Server 2017. When the rebuild is completed, you may notice that the newly built index is fragmented.
This issue is fixed in the following 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. Check out the latest cumulative updates for SQL Server:
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Learn about the terminologythat Microsoft uses to describe software updates.