H5p library and all contents don't display in Admin area and navigation bar of my WordPress site

Hello, I just noticed that H5P contents disappeared from the Admin area and navigation bar, all these contents can be shown up in the front-end, but in the admin area, they are invisible. even this page /wp-admin/admin.php?page=h5p is inaccessible to any roles who are permitted to access the admin. I have switched the theme to twenty-twenty and deactivated all plugins, H5p contents are still invisible. I don't know if it is related to my Chinese site because I have encountered the similar bug last year when I imported some contents from another site, as long as some titles of the contents are with this symbol “《》”,they can be used for titles, but importing files with this symbol would cause errors.  it may be an illegal symbol for h5p contents, this is just a thread for your reference. in case you need my site credentials for debugging, please let me know.

Best regards


Sorry, this issue was solved. After flushed web cache and Object cache again and again, H5p content displayed correctly. Thank you! :)