61 votesAaron Rothstein commented
Had users report this as well. The message history segment was present on their phone app, but not on their desktop app, and they didn't get a mobile notification because they were active on their computer at the time. When I had them quit and restart Teams on their computer, the missing messages appeared in the history.
Due to prioritization of other work-items this has been moved to the backlog. We will update when it is being actively worked on again.