This issue has been resolved, and new Threads comments should now be delivered normally. Our backup mechanism has also recovered recent comments that were delayed during the incident. We sincerely apologise for the disruption.

We've confirmed that an issue with the Meta API is causing the delay, and we’re working with the Threads/Meta team to restore normal delivery of new comments.
In the meantime, as a mitigation, we’ve enabled a backup mechanism to help recover recent comments. You can also trigger a manual sync by visiting the Threads channel page in Community or clicking Sync now.