I used a music file in the OGG format that had a pause at the end. In Audacity there were no gaps and playing on a loop in Audacity was perfect, only Gdevelop had a problem. Simply changing it from “Play a music file on a channel” to “Play a sound file on a channel” fixed the problem. Just thought I’d share that
Choosing “play a SOUND” instead of “play a music” as you advised totally worked for me !
Thanks