Signals Notebook: Unable to synchronize changes after editing file in Excel

In Signals Notebook, if an Excel document is opened using ‘Edit in Excel’ in ‘Protected View’, the following error may be shown on saving:

“UPLOAD FAILED. Your file wasn't uploaded because your changes can't be merged with changes made by someone else”


SOLUTION: In MS Excel options, "Trust Center" settings, disable "Protected View" for internet files.


NOTE: MS Word does not seem to be affected, only Excel and PowerPoint.