The most likely cause of this is that the folder of the document store is set to provide read permissions to a user group this user is not assigned to. By default, this would the the user group Everyone.
To check the user group that has permission for this folder, follow these steps.
In the Admin Tool, click Document Store.
Navigate through the document store to a folder containing documents or double click into a folder to amend permissions for a particular document (eg. Root Category - Policy Documents).
Right click on the folder or document, select Properties. This will open a window titled Document Category Properties.
Once you have identified the user groups that have read access to this folder, you can then assign this to the affected user via the following steps.
Under Configuration, click User & Group Management.
On the Groups tab, locate the group that the user(s) are to be added to.
Next to the group, click the black arrow to enter the group record.
On the Members tab, on the right, click Add Members.
Select the check boxes of the users to be added to the group.
On the right, click Continue. The user(s) have now been added to the group.
The group memberships can also be assigned to users via the Admin tool by following these steps.
In the Admin tool, click User Accounts.
Use the User Filter drop-down to bring up a list of users.
Double-click the user account.
Click the Group Memberships tab to expand it.
Next to the Group field, click Add.
Select the Group to be added to the existing user and click OK.
Click OK to save the action.
📌 Note: Once the user is added to the group, the notifications sent to the group will be received by this user as well.