The worksheet sort icons do not appear for me in 2018.
"To sort or summarize a group of database sub-rows:
If the database header rows are not displayed, select View > Database Headers from the Worksheet menu.
Select the header row of the group of sub-rows to sort or summarize; the header row has a diamond next to its number.
The three icons above the left end of the column header cells become available."
Nope. They don't become available.
I've just exported my file back to 2016, and it works. Feeling like I wasted my money on the "upgrade".