Hi,
I have this SharePoint list to which 'Everyone' have 'Contribute' permissions. In addition, my 'Advanced list settings' are set to the following:

The list contains a number of workflows and in the last very workflow that runs for each item I want to (temporarily) provide edit permissions to a single user to allow this user to attach a file to the item. Once the file has been attached I want the item to re-inherit the permissions from its parent, to avoid the list being filled with items with unique permissions.
I have played around with the 'Set item permissions' action in my workflow and it runs without any errors and when I check whom the item is 'Shared with' it says it has unique permissions and displays the user and the assigned permissions (as if everything was in order). However, when the user edits the item and tries to save it an error message appears saying that the user lacks the required permissions... Does anyone know what I am doing wrong here?
I have tried assigning different permissions levels and even with the 'Full Contol' permission the user is unable to edit the item.
