The reason they are covering it up, they have not even supplied the US with a virus sample yet despite repeated requests from the Americans, is because the whole world have a legit claim to sue them if it is proved the Virus came from one of their Labs, nations are already preparing to do exactly that.
One of the heads at that Lab in Wuhan has been studying coronaviruses for 15 years, she's China's leading expert, and they have published numerous studies about how they'd cracked how the virus spreads from animals to humans, 2 years ago the US had inspected the facility and had concerns about how it was being run, safety was not adequate.
I find it much more plausable there has been a breach at this Lab in Wuhan than the Chinese Govt claiming it started at a market selling bats.