I have an Add-In with its own Ribbon that works fine in Excel online but does not show the Ribbon in Excel on Windows [1]. There, it only shows the default task-pane.
To make sure it does not have to do with my own manifest, I verified this with the OfficeDev simple Sample manifest [2]. The only two modifications I did to the xml file are replacing 2 instances of Document with Workbook.
Also, I have verified this on two computers.
Why could that be?
[1] Microsoft Excel 2016 MSO (16.0.4266.1003) 32-Bit on Windows 10 [2] https://github.com/OfficeDev/Office-Add-in-Commands-Samples/blob/master/Simple/Manifest/SimpleAddin.xml