The Mario Mash-Up is not functioning properly on Switch. The music does not play, and the pipes do not launch the player properly.
(With Steve coming to Super Smash Bros. Ultimate, several of my Switch friends were interested in checking out Minecraft for the system, but it is hard to recommend when the one unique selling point for it isn't working as intended!)
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Thank you for your report!
However, this issue has been temporarily closed as Awaiting Response
Is this still an issue in the latest version? If so, can you please add it to the affected versions (or mention it if you are not the reporter).
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Cleaning up old tickets: This ticket had been set to 'Awaiting Response', but has not received a response from the reporter (~3 months+) so is being closed as Incomplete. If you feel this is still a valid issue then please comment, or create a new ticket following the Issue Guidelines which includes steps to reproduce the problem.
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What I did noticed was that in the Nether even though the original 4 background tracks were working, the 3 new background tracks don't change to fit the theme of this pack. I mean, I do love the track Rubedo, but it doesn't fit the theme of this pack (several Nether Update items do have different textures to fix the Mario theme though).