Just did a little quick testing, and multi-track background music behaves (almost) as expected. More on that in a moment....

Try renaming your music tracks with very simple file names - no punctuation, no spaces, no diacriticals. Keep it very simple: trackone.mp3, tracktwo.mp3, and so on.

Now to the "almost" part - browsers seem to be unable to autostart the background music if there are multiple tracks. I have no idea why - there are no errors showing in the browser console. It just refuses to autostart. One music file, no problem. This assumes that you're using the Triton Theme image splash page option - if you're not, autostarting the background music isn't possible, no matter what you do.

So, using a tool somewhere to combine your music tracks into a single file is definitely the way to go.

There's an unrelated problem with the slide's play/pause icons that shows up only on iOS browsers. That one is another mystery. I'm exploring solutions, but it's almost impossible to debug, and the difference between an album that shows the error and one that doesn't is elusive. Some Apple engineer somewhere is doing us a "favor" that we didn't ask for....

Finally, you'll find that testing your results on a phone is a bit of a nightmare. Phone browsers are very stubborn about using their cached versions of things. On a desktop browser, a quick CTRL-F5 is usually enough to clear things out, but on a phone browser, you have to plunge into the settings and get aggressive about clearing cached data.

The latest release cures the "non-automatic start of multi-track background music" and "weird iOS icons" problems.

Still curious about the failure to play a track in the list that you observed. I can't replicate that, even when I give the MP3 a weird file name, loaded with "problems" like diacriticals and punctuation.