I'm currently co-authoring a spreadsheet with another user. I can see the other user's changes in real-time and can see who last modified the file on File->Info. What I'm not seeing is an icon for the other user at the top right of the spreadsheet (there's no indication that it's currently being co-authored), nor am I seeing any color-coding for the changes they are making.
I'm in the desktop app and the other user is using Excel Online. I have a Microsoft 365 subscription and am running the most up-to-date version.
Is there anything I need to do to turn on co-authoring indicators (user icons, color-coding) or is the behaviour I'm seeing a limitation of my co-author using Excel Online while I'm using desktop?