Due to a misconfiguration overnight, a large chunk of Cloud Build’s paid-tier capacity was unable to accept new builds for several hours - leaving builds to be queued for processing on the remaining (unaffected) systems. This config issue has been corrected, and builds in the queue are being processed now - the queue is around half its size from 30 minutes ago, and should catch up fully within the next 1-2 hours.
The build queues have now generally caught up, and builds should proceed normally. The misconfiguration happened as part of some hardware upgrades, incidentally, as Cloud Build was adding capacity to keep up with increasing demand - but the team will be working hard to ensure further upgrades don’t involve incidents like this, and we apologize for the inconvenience.