Hi,
For the Document Library set as "Modern", when I create a new document from the button "New", it opens in Word.

But the connection with SharePoint is lost : the AutoSave is off and when saving the document, we are getting a pop-up asking to connect to OneDrive.

However, for the same Doc Lib, in mode "Classic SharePoint", it creates the document in the browser (not any more in Word), and then if we edit the document in Word, the AutoSave is on !
And the SharePoint properties panel is loading in Word.

The issue looks like it's coming from customed Content Types which are not well supported in Modern SharePoint.

So, could you please have a look at this ?

Thanks

Ticket :
https://answers.microsoft.com/en-us/msoffice/forum/msofficeword-msoother-mso_o365b/sp365-modern-library-new-document-disconnected/e644bc74-28d4-4667-b5c7-74143e1908d5?messageId=6253affc-9f2e-4abe-9cf8-7abf8bcc2a62