The international team of experts were going to work with scientists in the country to figure out how Covid-19 jumped from animals to humans.
Two members had already set off, but were then told their visas had not been granted.
Others were forced to cancel travel plans just before leaving.
WHO director general Dr Tedros Adhanom Ghebreyesus told a press conference in Geneva, Switzerland: “Today we learned that Chinese officials have not yet finalised the necessary permissions for the team’s arrival in China.
“I have been in contact with senior Chinese officials and I have once again made it clear the mission is a priority for the WHO.”
The mission was due to be led by Peter Ben Embarek, the WHO’s top expert on animal diseases that cross the species barrier.
He went to China on a preliminary mission last July.
WHO emergencies chief Mike Ryan said: “We trust and hope that is just a logistic and bureaucratic issue that can be resolved very quickly.”
Coronavirus cases were first reported in China’s Wuhan, and the initial cluster was linked to the Huanan Seafood Wholesale Market.
However, Chinese diplomats and state media have thrown support behind theories that the virus potentially originated in another country.
Senior diplomat Wang Yi recently said “more and more studies” showed that it emerged in multiple regions.
Ryan has previously called this “highly speculative”.
Wuhan hasn’t reported any new locally transmitted cases of Covid-19 since May.
At the end of January, it went through a gruelling 76-day lockdown that came with just hours’ notice and barred people from leaving their homes.
Roadblocks were erected and planes, trains and buses were banned from entering the city of 11 million people, the capital of Hubei province.
Almost 3,900 of China's 4,636 recorded coronavirus deaths occurred in the city.
The draconian restrictions began to ease in March, before the lockdown was fully lifted in April.
On New Year’s Eve, people packed the city’s streets and nightclubs.