This is a very specific bug.
1) Attach a document library to your teams that has some existing sharepoint documents.
2) when you do this, you can use the "get a link" to paste that into conversations, both the microsoft teams link and sharepoint links work (teams just allows you to edit in teams).
3) Once you have clicked the team link a "start a conversation" button shows up.
4) Click this and a new conversation appears in the channel with an attachment to the doc.
5) Click on the document and you will not be able to open it. This is not the correct function.
@Christopher Hoard sounds good. I did that in hopes it will be addressed. Thanks