You can always extract thumbnail images from protected DGNs (including i-models and packaged i-models) in the datasource when those documents have “Everyone” Protection, however by default you cannot extract thumbnail images from protected DGNs in the datasource when those documents have “Password” or “Certificate” Protection. If necessary, administrators can allow thumbnail images to be extracted from password or certificate protected documents by setting the following configuration variable:

MS_PROTECTION_NOENCRYPT_THUMBNAIL=1