Platform (Android, iOS, Website): ANDROID
App version number: v.1.27.4 
Screenshots of what you are seeing:
Description of problem:
Trying to add an observation with only SOUND element [birds] I get the error that is displayed in the image.
I’m going to translate it from Spanish to English:
Sorry, there was a problem loading sound from this source.
I have tried to upload the sound both from the option Record sound and Choose sound.
The same mistake is always repeated.
How can I solve that?
Can you describe the file you are adding?
( ;-) not all files are supported)
Yes, this is a sound file recorded from the Inaturalist app itself.
A recording where birds are heard singing.
Less than 10 seconds of time.
Reviewing I see that only sound files with WAV/MP3/AMR extensions can be imported.
The Inaturalist app when recording sound internally, which does not import, doesn’t use a native internal recording system of the app, but instead derives the default android recording app: “Sound Recorder [Android]” which save sound files with extension “.acc”.
Go into settings of the sound recording app and change the extension of the recordings.
I’m going to check that:
CHECKED. IT’S WORKING.
Please add internal recording functions from the iNaturalist app itself, it would save trouble.