Can't copy files via USB, just gets stuck on "Calculating the time required to copy"

I'm trying to back up my entire 20GB of data on my Note 4 before I wipe it and root it. I'd like to do that via USB because of how massive it is. But it's not letting me. I plug my phone into my PC, use the MTP connection method, and I can browse my phone just fine. I can even copy individual files just fine. But as soon as I try to copy a folder, or multiple folders, it gets stuck on "Calculating the time required to copy the files". Even if I only select two folders that only have a single text file each. A file copy that should happen near instantly, doesn't happen after hours.

I've googled the issue and it seems pretty rare - has anyone found a workaround for this? I've tried different USB cables, different USB ports, resetting the phone, resetting the PC, but nothing seems to work!

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