Hi Rose2211,
Great job exploring different fixes, like restarting the user and tweaking the roles. Another way to try is setting their access to administrator only. If that's not necessary for that user, just select Inventory Management under the company file roles, and be sure to tick all the boxes under the Manage Roles section within the Inventory Management tab.
If the issue still pops up after this, please connect to the team by creating a support ticket via MyAccount so our team can look further into it.
Cheers,
Princess