How do I play .webm audio on iOS (with a remote URL)?

I've written a short program that plays audio from a URL:

- Add remote URL "https://example.com/test/test.webm" (type "audio/webm; codecs=opus") as name "voice"

- Play "voice" not looping from Sounds at 0 dB (tag "voice")

I've exported this code to my website and it runs just fine on my PC. Unfortunately, I need it to work on my iPhone, too. But when I push the PLAY button nothing happens.

Any ideas?

UPDATE: I just saw this bug: "Audio remote url doesn't work in iOS #4721". Ashley says the workaround was to make sure to include .webm files in the program. All of my audio files are .webm, so I know that's not the problem.