Billed as an essential ancillary to the Olympic sporting events, the four-year programme kicked off in September 2008 as part of a government drive to celebrate cultures, people and languages.
Two agencies, Bolton & Quinn and Kallaway, were brought in last year to work on the Cultural Olympiad.
A major repitch was expected to happen next month, but so far London 2012 has failed to fire the starting gun.
One agency boss told PRWeek: 'There is a complete lack of transparency. There was a third round of tendering, which was supposed to finish at the end of March. We are trying to find out what's going on, but there is no response.'
Another said: 'There are a number of seething PR people out there. Lots of specialists are pretty miffed. Why are they precluding the good people in that space?'
But a London 2012 spokesman insisted it had not closed the door.
He said: 'We have a number of announcements coming up with regards to the Cultural Olympiad... We will review the situation around the end of March and make a decision about how to move forward. Absolutely no decisions have been made about this.'
Last year, 2012 chief Lord Coe claimed: 'The Cultural Olympiad will leave a legacy of cultural engagement in communities across our country.'
Projects in the pipeline include National Singing Day and Film Nation, a digital film competition for young people.
A World Cultural Festival will be held in 2012, featuring contributions from all participating countries.
But not everyone is supportive. The Daily Telegraph's Rupert Christiansen last year called the Cultural Olympiad an 'unnecessary distraction from the central business of the sporting competition'.