Comment 2 for bug 1921651

Also: if the colon is in the name of a directory you are copying, the directory gets created with the colon in the name, but any attempt to put files in it hangs.

Deleting the colon-named things via Files does seem to work, though.

And transferring files with spaces, dashes, and umlauts in the names works fine, too. It's just the colon that causes trouble.