I am having the same issue, however i have theme.scss.liquid as an option and none of these codes have worked.
these are the only options i have under assets. Using Venture theme
Goal: Keep the featured image on the blog list page, but hide it on individual blog posts.
Main approach (theme-dependent): add a small CSS rule to the theme’s stylesheet to hide the image within the article template. File names vary by theme and may be SCSS/CSS/Liquid under Assets. Access via Online store > Themes > Actions > Edit code, then append CSS at the end and save. Clearing cache may help.
Theme-specific CSS examples shared and confirmed by users:
Notes and edge cases:
Status: Multiple successes across themes; recent posts report missing legacy asset files and request updated guidance. Discussion ongoing.