Storing documents locally or in cloud services like OneDrive from within Microsoft Teams
Dear Serena,
Thank you for the reply.
As you also mentioned that the issue is happening with few excel file too and it’s random so in this case, I would recommend you contact your IT admin and raise a support ticket.
Reference: How do I find my Microsoft 365 admin? - Microsoft Support
Let admin help you create a support ticket in Microsoft 365 Admin Center>Support>New service request.
The support team there has the correct escalation channel for this kind of issue.
Appreciate your understanding and patience.
Sincerely,
AJ RAJ| Microsoft Community Moderator