If an asset metadata field is used to generate the filesystem path of where the file will eventually be stored after uploading in TeleScope, then versions of TeleScope prior to 2020.1 will be unable to generate proxy video previews if the metadata field of the asset had slash(es). The slashes were being used un-encoded to create the path rendering the path invalid, leading to the proxy video generation failing.
A fix was supplied in Telescope Executive 2020.1 in which the metadata field value was being encoded. It is recommended to upgrade to this or a later version. If your TeleScope installation has customizations or you're an OnDemand customer, please contact your Account Manager or support for further assistance with upgrading.
After upgrading TeleScope, uploading assets with slashes in metadata fields that are being used in the path should not lead to proxy videos not being generated.