When a job offer is put on hold?
When You Already Left Your Old Job and There's a Hiring Freeze. Unfortunately, a hiring freeze or a held job offer can happen after you've given your two weeks notice or even entirely vacated your last job. And, unfortunately, there's really nothing you can do about it.
Should you tell a job you have another offer?
Yes. You should definitely tell a company that you just received an offer from another employer. There's a psychological payoff to telling a potential employer that you've already received another offer. It shows them you're employable (exceedingly so)—and by the way, may not be available on the job market much longer.