This is probably due to the user's class access, or it's due to their review level access. Right-click on one of the cells and select "information". Review the user's class access to each dimension and also check whether they have access to the review level for the data (if you use process management).
This generally happens due to improper security class access. How are you granting security class access to the users - are they part of any particular groups / groups. If yes, are those native or external groups....is the user who has problems, part of those groups. For Standalone users, please make sure individual security class access has been provided and if part of any native / external group, please make sure to provision them and provide them with correct security class access.