Opening Excel document from Sharepoint creates a second window

r0uladen 

Same problem. As soon as my spreadsheet is moved from my local computer to either SharePoint or my personal OneDrive, opening it in Excel 365 does exactly what's described. I do have macros but they're in the Personal Macro Workbook, not any of the sheets I open. Closing the empty Excel window closes the workbook I want. My workaround (not solution) is:

1. In either Excel window, on the View tab's Window group, click Hide. This hides both windows but leaves Excel running. (The fact this works from either window also proves there's an association between the two, just like closing either window closes both.)
2. From the View tab's Window group, click Unhide and select your workbook. The unhides your workbook in the running window and doesn't re-open the empty window.

I have a little theory this might be related to hidden(?) temp files on the local machine that are necessary due to the source being SharePoint/OneDrive. It never happens with local files. It always happens with SharePoint/OneDrive files. It doesn't matter whose SharePoint I'm connected to, mine, a client's, etc.