m4a audio not playing on iPad

Hello.

Some of my members have reported that audio in H5P exercises does not work on their devices. After investigating, I found that the issue occurs specifically with M4A audio files. MP3 files work fine.

The problem happens only on Safari on iPads. Other browsers and devices do not seem to be affected.

Is this a known issue? Is there a workaround? I have hundreds of exercises with M4A files, and converting them all to MP3 would take a lot of time. Any advice would be appreciated.