Dropbox stuck on sync or index

I hope it is OK that I jump in on this thread, I new to this forum, so let me know if I should post somewhere else, but I have also been fighting this problem for a few weeks now.

Here all the details I can think of.

Machine Windows Server 2016 (basically the "Windows 10" server), version 1607, OS Build 14393.4169 latest patches)

Dropbox version 115.5.601

Dropbox account is a business account.

Dropbox installed using administrator account.

Dropbox folder has 145,588 files and they take up 24.8 GB, these are mostly relatively small text files spread out over lots of sub folders.

On average only about 150 files are added in an hour.  Customers drop in their files to be processed. the processing is done in non Dropbox folders, and once copied out, they are moved to a sub folder in Dropbox.

The sync locks up about once a day.  It is usually saying it is syncing a small amount of files like 2 or 3, but the amount changes from lockup to lockup.  Here is a screenshot of it both with the dialog open and hovering over the Dropbox icon.

Once it is locked up like this the only thing I can do is kill it with the Windows task manager.

If I select "pause" the "pause" never completes.

EDIT: I also selected the menu for showing sync errors, and it reports none.

If I then restart it, it again works for about another day before it lock up again.

Note that when the sync is locked up the icons on the files/folders in the Dropbox folder/sub folders to no have the Dropbox icon, just the standard windows ones, and the recent files what were being processed are locked (Windows lock).

Troubleshooting tried:

1. Reboot machine
2. Uninstall/reinstall
3. Ran the "hard link" permission function.
4. Tried both with smart sync on and with it off and only local files.

This is really quite critical for the company I'm working for because the model has been setup with the customers to just drop their files in their shared Dropbox folders and the server processes their files.  And Dropbox is used by the business too for internal use.

To change to another method for the customers to send their files will be "painful".

Thank you for any help you can provide.

Chris