What is the implication when a recruiter sets up an interview with you but then never follows up on it and stops responding to your emails/messages?

This is not the first time it has happened to me: An interested recruiter will contact me for a role I am a good fit for and sets up an interview, then when the day comes they never contact me. When I send a LI message or email to reschedule or attempt to follow up they ignore it. This seems incredibly unprofessional and a good way to lose clients, what could be happening to cause this? I am struggling to think what could be causing this, but it has happened to me on multiple occasions.

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