If an animation doesn't show after upload, try to wait up to 60 seconds.
These files can take longer to be processed.
If it doesn't work, please make sure you upload a valid .json file and refresh the page, and try again.
Doesn't show on the theme:
If an animation doesn't show on the theme while using the customizer, hit the "save" button. the page needs to be rendered again in order for it to show.
If you're using the "custom location" feature, make sure you toggled the extension.