You are misunderstanding what the “Item Details” are. That provides an extra field on the sign-up form (when a volunteer signs up) that allows them to specify the details of the item they are bringing. For example, I added that feature for our own school where we do staff appreciation lunches, and volunteers bring in various dishes for the lunch. So, the coordinator may want to have 3 main dishes, but wants each volunteer to specify the type of main dish they are bringing so that we don’t get duplicates. So, when somebody signs-up, they can use the item details field to enter the type of dish they are bringing, and then that will show up in that task/item list so other volunteers can see what dishes the other volunteers that have already signed up are bringing.
I made that item details field generic, so if you check the box for a task/item for needing details, you can then specify the label that will appear for that text input field on the sign-up form.
So, the plugin is working just fine. I think you were just confused about what those details are, or where you see the label text (it will be on the sign-up form).