Hi @son_gokou,
Please share some more details (like your site’s URL, for example) so I can help out. Otherwise all I can do is take a guess 😛
Thanks @son_gokou!
Alright, so the reason why thumbnails aren’t loading is very likely a conflict with another plugin. Please have a look here for more details and potential solution: Images not always loading.
If you have any questions at all don’t hesitate to ask.
Thanks for your help.
I disabled all plugins. Automatically the thumbnails appeared. Then I activated the plugins one by one, until I detected which one was causing conflict, it was the WP Total Cache. So I deleted it and installed WP Super Cache. Everything seems to be working properly!
Nice, thanks for the update!
I’m going to mark this topic as resolved then 😀
If you have any other questions don’t hesitate to ask.