Hi Alex,
Thank you very much for your response.
I have changed only the Post status to draft of all the 300 something posts.
Following the instructions here https://wpgeodirectory.com/docs/core-export/ what I did was:
1) Exported CSV of gd_place listings.
2) Opened CSV with Open Office UTF-8, comma as separator, double quote as delimiter.
3) Replaced all “publish” with “draft” in the post status column.
4) Save CSV.
5) Import in GD.
I have tried a couple of posts, both them had the issue. The featured image shows in photo tab in the frontend, but does not show in the header of the listing detail page, neither in the featured image and uploaded images section in the right column of the backend.
Then I assumed all the 300 something posts had the issue and I reverted the site to its backup. Therefore, the issue is not visible.
I look forward to your reply.
Thank you very much once again for your help.
Best regards.