Unable to stop transfers in progress

[Decoherent]

I accidentally copy & pasted a bit over 4,000 files to a SMB share. The problem is, I need some way to stop the transfer, rather than wait out several days with my phone plugged in. I've looked through all of the menus and options, and I am unable to find such a command. I can kill MaterialFiles manually, but as soon as it starts up, it continues the transfer.

I did see the cancel button in the shade, but all I managed to do is throw an I/O error that I couldn't dismiss :)

Is it possible to stop a paste transfer, or, could some such option be added?