If this occurred, it just means that the server creating the video had lost connection and therefore wasn't able to report that the video generation had completed.
To resolve this, simply refresh the page and head to the My Videos page to view your completed video.
*After your video begins generating, closing your browser or refreshing the screen won't cause it to not complete.
When is support available?
Read this link for support hours: https://support.wavve.co/en/articles/5373873-when-is-support-available-to-help-me