Teams is creating duplicates of files in private channels when adding a file to a post

Question

We run into a peculiar, but very annoying, bug that occurs in the new Teams regarding private channels:

We create subfolder in files in a private channel to keep all files organized.

We then create a post to alert people to a file in the subfolder. The moment one adds the file to the post, Teams makes a copy of the file from the subfolder and places it in the channel's root folder immediately, even before you actually submit the post.

Annoyingly, those who open the (copy) file via the post will read it and possibly work in it. Instead, the person who originally uploaded the file goes to the file in the subfolder and edits the original, assuming this is the correct and intended version. So you get two versions that will diverge.

In addition, your main folder will still be a mess of separate files.

If you don't submit the post or remove the attachment from the post before you send the post, the copy is also deleted.

If you (or someone else) makes a new post with the same attachment from the subfolder, Teams tries to make another copy and displays a message that there is already a version of that file.

If you delete the file from the root folder, the attachment in the post is no longer correct. In other words, it really refers to the (non existing) copy.

If you go in files to the document and there choose Copy link and place this link in the text of your post, it does work fine. Only then sometimes it opens within Teams and sometimes in the browser.

We have tested it. In in the old Teams version it worked as intended (the post had the original file) and it only occurs in private channels and shared channels (also a kind of private channel)

The permissions on the file and the copy are the same: any member of the channel may edit.

It doesn't matter what role you have within the Team. And both on Windows and Mac it goes wrong.