For a 360 viewer to recognize your 360 photo as such, your photo needs to be in an equirectangular panoramic format and it needs the standard 360 photosphere metadata. Occasionally, the 360 metadata is missing or is lost in the editing process. Exif Fixer can add or repair the missing 360 metadata.
Exif Fixer was made by Keith Martin (Twitter; Facebook) and is available here, for Mac or Windows. Exif Fixer is free but donations are encouraged.