Microsoft company has recently changed the way third-party services get access to view files in OneDrive for Business. Due to this reason, "View documents using Office 365" option is not available in Bitrix24 anymore, but you can still edit documents using Office 365.
What does it mean?
If you've selected Office 365 as a default document viewer in your Bitrix24, you'll be shown a blank window when trying to view a document.
What to do?
This problem can be solved by changing the default document viewer in your Bitrix24 Settings. Click Settings > View documents using and select Bitrix24 or Google.
How to edit documents in Office 365?
You can still edit documents in Office 365.
To edit a document in Office 365, log in to your Office 365 work account
(firstname.lastname@example.org). Then open the document and select the Edit in Office 365 option.