This is why camera pictures are flipped upside down on some Google Nexus 5X apps

A man inspects the Nexus 5X at an unveiling event in September 2015 (Justin Sullivan/Getty Images)

Some Google Nexus 5X users have noticed a minor but really annoying fault in certain apps.

Users have reported the camera viewfinder image being flipped in certain apps that use the camera. It's annoying because it makes the image seem upside down if you're trying to scan a barcode or take a picture within an app.

Fortunately for Google, the problem isn't due to a fault the phones - it's down to an odd issue with the unique construction of the 5X and an outdated camera API.

An Android engineer jumped into a Reddit thread about the fault to explain.

They said that most camera sensors in Android phones are mounted the same way - however, due to the shape of the 5X, the sensor had to be mounted in the less common, 'reverse landscape' position.

Android's camera API, which app developers use to make their app 'speak' to the phone's camera, has been updated since the release of the Nexus 5X, but many apps still use the old version.

This old version requires developers to explicitly set how the camera image on the screen should be orientated - but many don't bother, and leave it on the default setting.

This isn't a problem for most Android phones with the camera mounted the normal way, but with the 5X, it makes the camera image appear upside-down.

This isn't a huge problem for 5X owners, but it's fairly annoying - while major apps like Instagram aren't affected, apps made by smaller developers who may not be using the latest API could be.

Google could adjust the default rotation setting for the 5X, but that would have broken the apps that use the old method.

Google is now reaching out to developers to bring their attention to this issue, and they're also encouraging users to alert developers if they notice it affecting an app they use.

It's a pain for users of Google's flashy new smartphone, but hopefully the issue will be sorted soon.