I cannot replicate, for me the playlists are properly copied both in Media Tree and file listing (Grid)

i.e. I right-click a playlist item > Copy, right-click another playlist item and select > Paste
=> the playlist is pasted as expected (and copy created)

The only case when it does not work for me is if I want to copy a playlist and want to paste it to its parent (where it already exists).
Is this the case that you tested?

i.e. this works:
1) Right-click Playlists -> PlaylistA > Copy
2) Right-click Playlists -> PlaylistB > Paste
=> PlaylistA is pasted to Playlists -> PlaylistB as expected creating new playlist
Playlists -> PlaylistB -> PlaylistA

i.e. this fails:
1) Right-click Playlists -> PlaylistA > Copy
2) Right-click Playlists > Paste
=> it fails to create duplicated Playlists -> PlaylistA

Is this what you are observing?

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EDIT: The case of failure to create duplicate playlist on the same parent will be fixed in 2406

Thanks for reporting, I'm able to reproduce. Added as: https://www.ventismedia.com/mantis/view.php?id=17863

I think I've found a small bug. I wanted to copy an auto-playlist, so I could tweak its settings. (Basically, change it from "stuff i added yesterday" to "stuff I added in the last week"). The copy-and-paste routine didn't work. Not sure if the fault's in Copy or in the Pasting, but it didn't work.

Windows 10, MMW5.