Hi Janis. That is a known issue. The problem is that Chrome on iOS is really a wrapper around Safari and does not expose the APIs we need to access the microphone. So we default to showing an upload button. You can record video from that and we just convert it to MP3 when it arrives . Or ask the student to use Safari. Sorry about that.
Thanks for getting back to me so quickly. I suspected this might be the issue - we have problems with some H5P activities in Chrome for iOS users too.