Cloud Scheduler Crons Failing Only in Staging Environment (No Logs)

Question

Context:

I have two environments, prod and staging, that are mostly identical (prod just has a larger Cloud SQL DB instance). In both environments, I use Cloud Scheduler crons set to run every minute ("* * * * *") and trigger Cloud Run batch jobs.

Problem:

In recent weeks, and only in the staging environment, Cloud Scheduler crons are regularly failing to run, usually for a few minutes in a row but sometimes for periods of up to an hour.

During these gaps:

• There are no logs in Cloud Scheduler (no successes or failures). (protoPayload.@type="type.googleapis.com/google.cloud.audit.AuditLog")
• Cloud Run job logs show no activity during the gap (no job starts, or fails to start)

After the gap:

• Cloud Run logs show a bunch of "Execution {id} has been deleted." messages.

Troubleshooting Performed:

I checked all of the easy things:

• cron expressions are correct
• no quota seems to be hit (or even close)
• permissions are OK

Question:

What could be causing Cloud Scheduler crons to silently fail/pause ? What could cause it to happen only in the staging environment?

I'm at a loss for further troubleshooting steps. Any insights or suggestions on how to diagnose the root cause of these cron jobs not launching would be greatly appreciated.