Media Library not showing thumbnails

After wordpress move to another web hosting, media library can not display thumbnail.
I was using FTP upload the “uploads folder” from old web hosting to new one.
Permissions have been confirmed, it’s no problem.
I can also upload pictures from the dashboard.
But I do not know why, the images uploading from FTP in the media library can not be correctly displayed thumbnail.
FTP in the archives are present, the site also can browse pictures, you just do not see diagram in the background media library.
WHY WHY WHY WHY ????