Hi Arthur,
Thanks for contacting Syncfusion support.
When the Access permission is denied for file actions(for ex: delete) in File Manager, the confirmation dialogs will be opened. But when the delete action is confirmed, an access denied dialog will be shown for the users to know that the corresponding action(delete) is denied. Can you please confirm whether the file/folder delete action occurs at your end when you click the confirmation button for delete action?
If so, please share the file service provider and package version to check further and provide a prompt solution.
Regards,
Keerthana R.