Problem with attachment in Apple mail

1) On the computer where I'm having problems with email attachement, backup is turned off.

2) Yes, I see some folders, because in the past I had activated the backup, but now I haven't used it for months.

The dropbox location is:

Users/**/Library/CloudStorage/Dropbox

To attach documents to Apple Mail I have tried every possible way.
1) Drag and drop the document into the message with the mouse.
2) Click on the button (with icon) inside the message.
3) "File" menu, "Attach file" command.

The current situation is as follows:
1) I can send attachments contained in dropbox only from outlook. With Apple Mail or Spark (Readdle) it is impossible to.
2) I can attach documents to emails (Apple mail and Spark) only if I first move the document to the "downloads" folder.
The location of the folder is : Dropbox / Mac (5) / Donwloads
Even if I move an attachment from a dropbox synchronized folder to the desktop and then attach it to the message, it doesn't work.

Update and supplement to previous message

Update:
In addition to what was written before: I can attach a document to an email message if the attachment is in the "Documents" folder.
Address: User / Laurent / Documents

Supplement
I found another problem: When I receive a message with multiple attachments and I want to save the attachments with the "save all" command. I choose the folder where to save the documents, then clic "ok". It seems to work, but then I open the folder and it is empty.
If for the same operation, I choose the "Downloads" or "Documents" folder for destination, everything works correctly instead.
If instead I drag in attachement from the email message to the folder I want with the mouse, instead everything works correctly

Hi Megan, here are attached screenshots of the Backup preferences

Hey Megan

The Synchronization is always updated.

NEW
I upgraded the operating system to MAC OS 14.4.1.
But nothing has changed.

I did a test: i deleted old dropbox backups. (backup was no longer in use anyway).
Now the "downloads" folder is gone. I can't tell if it is due to this operation or the 14.4.1 system update.

Now I tried uninstalling dropbox completely and installing from new dropbox, but unfortunately nothing changes. I can't attach documents to emails in App Mail.

Another thing I noticed, that when I start the OS, sometimes (not always) dropbox struggles to start and I have to close and reopen it. is this normal? (However, this also happens on other macs where I don't have the attachment problem).

Another question: is it normal that when reinstalling dropbox, it keeps a copy of the old dropbox (with the date of the change) in the mac os x "cloudstorage" folder (see screenshot). The old folder has all the folder hierarchy, but not the contents thankfully.

Hi Jay, I already announced to support and they replied that the problem is known and that engineers are working on a solution. But I haven't had much support and a feeling that my problem is being taken seriously.
I wanted to write here in the community to know if other users had experienced the same problem as me.

I have not found a solution to the problem, but I have bypassed it.
I created a new profile in Mac OS X and now everything seems to work.

Hi Graham, thank you for the information. Before contacting the community I had contacted the dropbox technical service. They had replied that the problem was known and that engineers were working on the problem, but I did not get much support.

The bypass solution I found is not a perfect solution, but it allows me to work with customers every day. I still have one problem that I cannot understand: I can only attach documents if I use Apple Mail. In some cases I have to use Spark from Readdle, but I cannot attach documents.

In all cases you can contact me at the email linked to my account.