Excel 365 Sheet Views are not working

PFonseca 

Some XLS files cannot be viewed in OWA

The problem can be observed as soon as the following constellation occurs (note the AND links):

    The old XLS file type (the problem does not exist with the new XLSX format).

        AND

    View> Break preview is activated in one of the data sheets.

        AND

    SharePoint or OWA is used for viewing.

A solution as far as I could research on the internet has not yet been found.

The possible workarounds can be seen below.

Workaround 1:

Convert existing files to the new XLSX format

To do this: Open the XLS file and then "Save as", file type "Excel workbook (* .xlsx)".

Save new files only in the new (XLSX) format (because only this can be edited in the browser via OWA).

Workaround 2:

In the existing XLS files, switch from "View"> "Break preview" to "Normal" e view.

Or toggle in the status bar of Excel

This has to be repeated in a file for all sheets that have activated the "Break preview" view.

Then save (and upload) the file.

Link: XLS files and Office Web Apps

https://social.technet.microsoft.com/Forums/azure/en-US/95c1e237-bcf0-4c15-ae2e-d96a019289df/xls-files-and-office-web-apps?forum=sharepointgeneral