After playing around for a day or so with Teams, I decided to try and convince my office to switch from Slack. My first demonstration of creating channels (after creating multiple ones yesterday) failed as they would disappear immediately after being created. This is in the desktop and web apps in Windows and on Mac. Logging out and back in does not solve the problem. Needless to say, this failure of a demonstration is forcing us to continue using Slack. Maybe we will try again next year.
Nick Kintanar commented
This happened to us as well, but it worked the next day. One thing I noticed is that it still created the channel directory folder in the SharePoint library.
Also it took 9 hours for GIF integration to work after it was enabled.