Dear @iko79,
Welcome to Microsoft Q&A forum.
We apologize for any inconvenience you are experiencing with the Excel Desktop App. To better understand and assist you, could you please confirm the steps you have taken so far:
- After accidentally saving the file to your local PC, you clicked on the file title and selected [Upload your document], as shown in the screenshot below.
- You were then prompted to choose a location: OneDrive for Business, OneDrive (Personal). Could you let us know which option you selected before the issue occurred?
- After selecting the location, you would typically wait for the upload to complete.
- Then, when choosing [OneDrive - tenant name], you encountered the blank screen you shared.
Additionally, could you please provide the following details:
- When was this feature last working for you?
- Does it work if you use the Save As option and select the OneDrive location?
- Is the issue also occurring in PowerPoint and Word?
- What Windows version are you currently using?
- Do you currently use VPN, firewall or antivirus software running in the background? If so, could you temporarily disable them and try again to see if the feature works?
If the steps above do not match what you performed, could you kindly share the exact steps you followed? This will help us support you more effectively.
I am looking forward to hearing from you.