Works for me Mint 19.1 Nemo 4.06 (fork of Nautilus 3.4 without the functional downgrades of 3.6) and works with cp on the command line.
08:23:22: Geany INFO : Geany 1.35 (git >= c4f5878d), en_AU.UTF-8 08:23:22: Geany INFO : GTK 3.22.30, GLib 2.56.3
@andy5995 @codebrainz Please show date/time of `file1` and `temp/file1` before and `file1` after the copy.