This article will cover what causes this problem and how you can fix it.
If you have been using Snapchat for quite some time, then you are probably familiar with the loading screen that appears when sending a new snap. You may have noticed that sometimes the loading screen won't go away or that it goes away just to reappear later on in your conversation with another user. The reason for this is because Snapchat needs more time to process the image or video you are sending so that it can be sent successfully without any errors occurring during transmission.
Read More: https://www.guidebrain.com/fix-snapchat-not-loading-snaps/