Dropbox syncing files already deleted from laptop and Dropbox

Hey there Kismuntr​ welcome back to the community,

Can you confirm whether you have Dropbox Backup or external drive backup enabled for this external hard drive or the deleted folder?

You can find this by opening the dropbox desktop app, clicking your name/icon in the bottom left corner, opening preferences and clicking the "backups" tab. 

Hello!
No backups exist (and no backup function seems to be enabled), neither on the main laptop nor the external hardrive (which is not permanently connected to the laptop, if that is any help).

The screenshots are in German so I hope they help:

Hey Kismuntr - thanks for the screenshot and guten Abend von mir. 

Can you please clarify if the folder you deleted was available offline on your computer or online-only? 

If you still see it in the web browser, can you try clearing your cache and/or another browser to delete it again and let us know how it goes? 

It was available offline, not in "online-only". And I did delete it in the browser (directly on dropbox.com by logging in and deleting it there). I cannot see it anymore (on neither of my dropbox connected devices. The folder is, according to those devices, deleted. Neither accessible through an app or any device directly. I also cleared the cache (Dropbox\.dropbox.cache).

In that case, I'd suggest letting the app sync your changes until it's 'up to date and if you still face any issues afterwards, just let us know and we'll take it from there. 

Thank you Walter​!
One last question though. Is the number supposed to be stuck?
Because the app says it syncs but there is no progress. It is still showing 96.665 files syncing/downloading (tried restarting the desktop app, restarting my laptop, same result).
The app itself is sully accessible. I can pause the sync, access settings, etc. It just seems the syncing process is stuck.

I see, thanks for letting me know about this.

Have you tried quitting the app and/or rebooting your computer since you first noticed this? 

If you did and the number remains the same, you can try fixing your hardlinks and permissions.

Keep us posted anyhow! 

The app has been rebooted. Laptop has also been rebooted. 
"Fix Permissions" does not register (no reaction, just the button flickering upon click). 
"Fixing Hardlinks" gave me a prompt that hardlinks are being fixed, but no effect on the stuck sync. 
Rebooted the app again and now it seems to register that I saved new files (the screenshots shared here) but it hops around between the numbers 96.665 - 96.667 with no further progress.

I logged into dropbox directly from my browser (firefox) to check if the files might still be there but I deleted them permanently so there shouldn't be anything left for dropbox to sync/download.

Hi there, Kismuntr, is the syncing still stuck like that?

Also, how many files do you currently have in your Dropbox folder?

Hello Hannah​ 
Yes, the sync is still stuck. I checked in with my other connected devices (Android Phone, Ipad, and a second laptop) and all those devices are fine. No syncing troubles. They state everything is up to date. It seems to be just this device. 

I have several hundred thousand files, as I am an artist and photographer and store all my pictures, photos, references, etc, on dropbox.
(I am running a properties check on my Dropbox folder and will update as soon as possible with the exact value).

Here a screenshot of the main folder that contained the subfolders I deleted. The main folder shows the syncing symbol but inside everything is up to date (and the folders I deleted are actually gone, both on this device and on dropbox.com)

Edit:
I got an error message from my device about storage space running low and checked the Appdata folder connected to dropbox. Could this perhaps be connected to it?  
Because the main reason why I deleted all those files was exactly that. I moved a big amount of files, storage space ran low (due to Appdata filling up), I transferred those files to an external harddrive and deleted the folders/files on my device and dropbox.com in hopes it would not sync anymore and not further fill the Appdata folder, it synced fine once, then it began resyncing all those deleted files. And now it seems to be stuck trying to still sync files that are not there anymore.

Edit 2:
Now syncing jumped to 146.239 files. No change in the folders coming from me besides saving the screenshots that I am sharing.