Conversation File Type Filtering

I feel like I am missing something obvious. Where do I expand or contract the allowed file types used for conversations (private messages)?

I have added more types to the global list in Moderation, but the conversation tool seems to still be restricting to a smaller list. (Not a caching issue that I'm aware of since the additions happened months ago, but complaint was recent)

Previous sources of documentation I've looked at for guidance:
How can I control the types and sizes of files that members can upload outside of specific applications? - User Documentation - Verint Community 11.x - Verint | Telligent Community
How do I control types and sizes of files that members can upload? - User Documentation - Verint Community 11.x - Verint | Telligent Community