macOS Monterey 12.0.1
DropBox for Business 47TB
Drag & Drop of a folder with 8 media files in it starts to upload, creates the sub-folder, and shows the first file as uploading. Stops incrementing bytes at 50% of the size of file #1.
At this point stopping the transfer does not work & disconnection does not work. The only recourse is to force quit NetDrive3 which leaves the icon for the drive on the desktop. It will not dismount and restarting NetDrive does not give control back.
In order to resolve the problem, NetDrive3 has to be forced to quit a second time, and Finder needed to be relaunched to disconnect the drive.
No caching is enabled and NetDrive3 is set to always get the file listing from the server.