Due to a new assembly-method, the image sensor inside the Nexus 5X was installed in a different orientation (landscape) to make the wires fit. As a consequence, Google had to tweak the software to ensure that your snaps wouldn't display upside down. Unfortunately, plenty of third-party apps didn't bother to update to the firm's latest imaging APIs, and as such all of the pictures that you take with them are all screwy.
Esko will update the API for the Android App in order to solve this issue.