I was used before canvas theme from Woo themes. When I used that theme, there is no problem in thumbnails. If I changed to any other theme, latest posts doesn’t have thumbnails. Nearly 50 posts don’t have thumbnails. Please, help me!
I think that your Woo themes was saving the thumbnails as a custom field that is later visualised. Check out your previous theme and where exactly it loads the thumbnails from. Then make sure your current theme loads them from the same place.
Check out the index.php file in the Woo theme. Try to locate the thumbnail generation code and compare it with the one of the theme you’re currently using. Note that this may not be an easy task and some development maybe needed.