Workfront Widen DAM Integration Issue - Thumbnails, Preview and Download not working

Dear Community experts - We have been trying to integrate Widen DAM with Workfront using Custom Integration and through Document Webhooks(Document Webhooks API | Adobe Workfront), below are the list of issues which we have been facing - 

1. Every file type/format uploaded using Widen DAM as document provider, the extension of file becomes as (.unk)

2. Preview doesn't work for files

3. Download gives an error 

Thumbnails endpoint are not getting triggered, after inspecting the source we see few errors that below endpoint is getting triggered for thumbnails for assets added from custom webhook - 

https://"domain".workfront.com/internal/document/externalThumbnail?type=WEBHOOKS&providerID=6613afb0000edbcd769373287f25c7e4&ID=86b4a4d6-dd19-487b-86ae-969770f4ad68

whereas when we add assets from one drive below endpoint is getting called for the thumbnails

https://"domain".workfront.com/internal/document/externalThumbnail?type=ONEDRIVE&providerID=661511360010ecf23d0802d3a2c1361a&ID=b!a3KctnZELUiXFG626mJ4nInFO0i5wEpCtkpXkiBczOPPel6vcKrWQYY3hnriJgoH/items/01OKPBP7RA53KMRBHZAREYCOLLWTGSKL4J&date=1712347099000

Has anyone faced issue liked this for any of the custom integration or for Widen DAM specific?