Task sorting doesn't work - postgreSQL

I use PostgreSQL and want to use drag and drop in order to sort my tasks.
I checked your guide and I enabled it.
On my DB all the values in the column “sortorder” update correctly but when I refresh my page reordering seems to be ineffective.
How can I fix it?
Thank you.

Can you please try to enable log and check which SQL code was generated for data loading, it must contain a SORT BY clause.