In this topic tutorial we’ll help you resolved the issue Instagram has returned invalid data. However, maybe have other reason cause this error. Please comment if you found an other solution!
Update: Instagram has just updated their API and now we can’t get images gallery use @username. You only can use #hashtag to get images. If you need get images gallery user @username you can use an other plugin here: https://wordpress.org/plugins/instagram-feed/
Instagram recently started to block servers/IPs that are requesting its images. Some servers are working fine, but this usually happens if the website is on a shared hosting plan. So you can contacting your hosting provider help you resolve this issue.