Hello,
Could you provide a video or screenshots? Describe the situation in more detail so we can try to re-create it on our test site.
Watch this video – https://youtu.be/4n1re0jKorc and read this article – https://help.market.envato.com/hc/en-us/articles/202821510-Theme-is-missing-the-style-css-stylesheet-error
Regards