I'm glad to hear you solve the problem, if you have any issue about SharePoint, you are welcome to raise a ticket in this forum.
By the way, since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others.". So, I would make a brief summary of this thread.
You could click the "Accept Answer" button for this summary to close this thread, and this can make it easier for other community members to see the useful information when reading this thread. Thanks for your understanding!
[I am having a trouble with the Autosave with one specific Microsoft excel Spreadsheet on my windows 11 computer]
Issue Symptom:
OP have never changed the way the shared spreadsheet is used, however a few days ago, the autosave ceased to function. OP do not believe the file is not too big and all of coworkers do not have trouble with this issue. This is the only shared spreadsheet that is having this issue on the end, others work well as intended.
When OP go make an edit, no one can see it at first. The only way OP can save changes made is manually by clicking save or closing the application and it is prompting to save.
The shared spreadsheet is stored in SharePoint, OP also use OneDrive as well. OP see both are labeled as "Connected Services" on Excel. And have no add-ons and my Autosave is on in excel options.
Excel Version: 2501 (build 18429.20158) Windows Version: (Windows 11 Business)
Current status:
OP solved this. Through enable AutoSave button at the top left in the excel.