The bug
After re-loading (and getting the Mojang Studios loading screen), the Minecraft music stops for 5 minutes or so until it plays again. This also happens with jukeboxes.
What I expected to happen (with the Minecraft music)
I expected it to pause the Minecraft music and then continue playing after it's reloaded.
What I expected to happen (with the jukebox)
If it's on singleplayer, I would expect it to pause and then resume the music disc.
If it's on multiplayer (or a LAN world), then I would expect it to not pause the music disc, but instead just to resume it where it's at server-side.
How to replicate (with normal background Minecraft music)
Wait until Minecraft plays a default song (for example C418 - Wet Hands).
Reload your resource packs (F3 + T), or get Minecraft to go to the Mojang Studios loading screen.
How to replicate (with jukeboxes)
Play a disc in a jukebox (for example, Pigstep).
Reload your resource packs (F3 + T), or get Minecraft to go to the Mojang Studios loading screen.
Note
Does it work even without mods and with the original launcher?
Yes.
Thank you for your report!
However, this issue is Invalid.
Your game, launcher and/or server is modified.
If you can reproduce the issue in a vanilla environment, please create a new ticket.
Any non-standard client/server/launcher build needs to be taken up with the appropriate team, not Mojang Studios or the Bugtracker.
Any plugin or resource pack issues need to be addressed to the creator of the plugin or resource pack.
If you have problems on large servers, such as The Hive and Hypixel, please contact them first as they run extensively modified server software.
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