It does appear to be issue with PayPal.
PayPal IPNs say "Queued", rather than "Sent" as it was back in October thread.
PayPal also just updated their status page about Service Disruption for Notifications. https://www.paypal-status.com/history/eventdetails/8150
"Initial Notification: We are experiencing a system issue which is affecting Notifications on the Production environment. PayPal Merchants may be experiencing delays receiving Instant Payment Notifications (IPN). Our technical teams have been engaged and are actively troubleshooting the issue.
Nov 10, 16:23 UTC"