Even with extended access and/or DDA settings set to default to automated or unmediated access in LibCentral, there are still some situations in which it is possible to get a mediated request for a title. If you receive a mediated request you are not expecting, here are some possible reasons why.

1. STL/Autopurchase per-patron limit has been reached.

Example: If you have set an STL/Autopurchase limit per patron and the patron exceeds that daily or weekly limit they will have to submit mediated requests if they trigger additional titles.
This setting can be viewed or changed in LibCentral under the General tab in Access Permissions Details

The “Permit Mediated Requests” setting under the General tab does NOT need to be set to “Yes” for a librarian to receive a request for an autopurchase that has exceeded the copy limit for a book.

2. Extended access enabled and set to upgrade automatically, but no upgraded license is available.

Example: A library owns one user copy of an ebook and the ebook is currently in use. The library's Extended Access settings permit for an auto-upgrade is another user attempts to access the ebook while in use. This ebook is only available with a one user license, so cannot be auto-upgraded. When an ebook is not available for an upgrade, the request will be mediated. Please refer to this article for more details about Extended Access settings:
Extended access settings may be viewed or edited in LibCentral under the Owned tab in Access Permissions Details.

3. DDA settings allow for non-mediated STL’s, but a  mediated request for a DDA title occurs due to checkout length limitations.

Example: Checkout lengths for DDA are limited, or in other words if only one day and seven days are selected for a DDA checkout and a DDA title only allows a 14-day checkout, then a mediated request may be received.
Checkout length duration for STL’s may be viewed or edited in LibCentral under the DDA tab in Access Permissions Details.