Cannot save changes to Microsoft Word Online documents in shared Dropbox folders.

Greetings.

The issue.

Any MS Word document that I create in a shared Dropbox folder or add to the folder cannot be edited in Word Online without getting the following error message:

Couldn't save latest changes. To avoid losing the highlighted changes, copy and paste them into the document in a new tab.

The message is in a yellow banner at the top of the document.

Specs.

I'm running Firefox Developer Edition 114.0b9 (64-bit) under Debian GNU/Linux 11 (bullseye) x86_64. I have a free "Basic" Dropbox account, and a free Microsoft account (no 365 license).

Things I've tried.

• I've tried logging into my Microsoft account, reloading Word Online, and trying again. I even tried recreating the entire document when signed in to my Microsoft account.
• I've tried creating the document in another subfolder  of the shared folder.
• I've tried different formats, including ODT, DOCX and DOC.
• I've tried adding MS Word files to my shared folder in different ways, that is:
  1. By using the Dropbox web interface and its "Create" dropdown;
  2. By copying and pasting a file into the shared folder, again using the Dropbox web interface;
  3. By adding the file to the synced folder on my Linux system.
• I've tried setting the share options in Word Online to "Anyone with [the] link can edit".
• After each of all these different attempts, I would reload the document and try to change the file again, with no success. I would also close the tab and reopen the document afresh from the Dropbox interface. Even after doing this, the same error appears a few seconds after making any change, whatever that be, to the file. Some examples of different changes I've tried making to the document include adding text, removing text, changing the spell check language for the document as a whole, changing the font of some or all of the text, adding comments, and so forth. Doing even a single one of these changes results in the error described earlier, meaning that the number of changes made to the files is unrelated to the problem, as opposed to what some have suggested online on other forums.

A quick search on the internet shows that many people are complaining about the very same issue to Microsoft, although Microsoft staff argue that this is a Dropbox-related problem, and don't suggest any working fixes. I say this in all due respect to both Microsoft and Dropbox staff and community, and am not accusing anyone for the problems I am experiencing.

It is noteworthy that this error does not occur when creating or adding an MS Word file to an unshared Dropbox folder.

Any help would be greatly appreciated. God bless.