Rebuild Index Task options I have to debug a performance issue on a SQL Server 2016 database. The query was pretty simple - a few temporary tables joined with SQL tables and aggregation. The amount of rows of involved in temporary tables was really small (several tables, hundreds of rows).
I have found that one of the tables PK has 12% index fragmentation. If the table was removed from the query it runs faster. I rebuilt the index and everything was fine.
I believe there must be something wrong with the settings of the SQL Server 2016 instance, because the query is running perfectly fine on SQL Server 2014. The only difference I have found in the settings was in the maintenance plans - the pictures below shows the plans:
SQL Server 2016

SQL Server 2014

I guess there is something not set correctly in the Index Stats Options, which is causing statistics not to be recalculated. Can anyone tell me if am I am right (as I am not DBA) or say if the plan looks OK, so I can search for the issue in another place?
This is longer than a comment .. so putting this as answer ...


  So, I have rebuild the index and everything was fine.


Rebuilding an index will update stats on the columns associated with that index.

There can be a lot of variables which might be different between 2 servers (2014 vs 2016) 


sys.configurations settings
compatiblity level of database
Any custom trace flag enabled
max memory setting
cost threshold of parallelism setting
max dop setting


You can run Best practice analyzer script from MSSQLTiger team or just run sp_Blitz from Brent Ozar's team.

As a side note: Use Ola's Index maintenance solution ... much flexible and well tested by a lot of organizations.

From your screenshot, it seems that you are setting the page fullness (FILLFACTOR) to 80% i.e. leave 20% free. You should monitor fragmentation (in your case 12% is nothing + you need to consider how many pages are in the index. I would suggest you to start looking into indexes with 1000+ pages). I would doubt that this will cause a major performance problem.