I posted this in the forum for mp3-jplayer, but the developer hasn't answered posts for the past 9 months.
After upgrading WordPress 3.42 to 3.5 yesterday, mp3-jplayer broke in Safari and Chrome for Mac, and Mobile Safari and Atomic Browser for iOS. Symptoms are many, including: playback failing to start when a song title is clicked; multiple song files being highlighted at once after they're clicked (instead of successive clicks selecting a new song and de-selecting the previous one); 'current time' readout remains at 0:00, and total time readout is missing; clicking on a song title sometimes causes a jump to the top of the page; playback progress head fails to appear; and more.
The players appear to be working fine in Firefox.
The problems remained after I tried the following:
1. disabling all other plugins
2. switching to the new Twenty Twelve theme
3. running SCRIPT_DEBUG as recommended in the Codex
Uncaught Error: cannot call methods on slider prior to initialization; attempted to call method 'option' query.js:2
Occasionally, clearing the browser cache and re-loading the affected pages seems to resolve the issues in Safari, but this is not consistent.
All running in Mac OS 10.8 on a Mac Pro 8-core
Also: latest versions of Mobile Safari and Atomic Browser on iPad2, iOS 6
Test page is here.