Unable to Access User Mailbox with Full Access Permissions through OWA

Hi everyone,

For whatever reason, I'm not able to access any accounts that my administrative account is granted "Full Access" to through the EAC. 

Whenever I try and open the other users mailbox that I have permissions for, I get the following error:

something went wrong

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X-OWA-Error: SDServerErr;Microsoft.Exchange.Data.Storage.AccessDeniedException
X-OWA-Version: 15.0.847.32
X-FEServer: EXCH2
X-BEServer: exmb1.contoso.com
Date: 1/2/1601 2:51:36 PM