My earbud port is VERY temperamental. If I move at all when playing, the sound either fades out or completely cuts out and I have to move the earbud’s plug in around to get the sound back. I know it’s not the headphones because I try three different pairs. I only had the Fuse for a few day.
It sounds like you probably don’t have the headphones plugged in all the way. When new, the jack is very tight and may require a bit of effort to get the plug in fully. Push the plug in a little harder and your problem will probably disappear.