I'm no longer receiving LINE messages but there are no errors in my Social Messaging settings.
In LINE Official Account Manager, Response mode should stay as Bot mode. This setting can be found under Response settings > Main settings. Changing this to Chat mode will automatically disable Webhook in LINE Developer Center.
Enabling the Bot option and the Use webhook option in LINE Developer Center should fix the issue.
For more information about the LINE integration, see this article: Setting up your LINE or WeChat channels.