Why "Create Item" is inactivated in Product Management

Summary:

Please tell me the reason why "Create Item" is inactivated in Product Management(Redwood)

Content (please ensure you mask any confidential information):

Hi, experts.

It seems that "Create Item" is inactivated in Product Manegement(Redwood), then we can't create new Item in Product Management.
I can't push "Create Item" when my cursor is over.

However, I can create new items in Product Information Management Menu.

Please let me know the reason…(maybe priviledges, opt-in or lisence?), and any solution.

Navifation Path:

Product Management > Product Management > Action: Items > "+"button > "Create Item"

Version (include the version you are using, if applicable):