Cron Job Scheduler no longer accepts range values

[DataEngineer]

Greetings!

This morning I went to update a schedule for a workflow configuration and was met with an error that my cron job schedule was no longer valid. This is despite the fact it's been functioning without issue since its inception 12 months ago.

Error message:

This schedule is even the exact example used in the documentation hyperlinked in the above screenshot - "unix-cron" (https://cloud.google.com/scheduler/docs/configuring/cron-job-schedules#defining_the_job_schedule)

So I'm at a loss for words.