Workbench section not showing in apache jmeter

You can find all features of Workbench here:

Navigate to Test Plan -> Add --> Non-test Elements, now you could see all required features of Workbench

It's not a bug but a feature since JMeter 4:

Workbench has been dropped from UI, you can now use Non Test Elements as immediate children of Test Plan.

You can now use elements in Test Plan as you used previously in Workbench

You can see also an old question that asked why workbench is shown in the first place