As the thread notes, China says 2/3 of asymptomatic cases develop symptoms and get reclassified as confirmed cases. But Hubei has reported 303 new such cases but just 2 such patients developing symptoms and become confirmed COVID-19 patients. https://twitter.com/Rover829/status/1248101565753446406
China started reporting asymptomatic cases on a daily basis since April 1. The fact that there have only been 2 patients so far this month developing symptoms while a total of 303 asymptomatic cases are reported and 852 such patients are released is odd.
For all of mainland China, the NHC has reported 657 new asymptomatic case so far this month and that 57 asymptomatic cases have developed symptoms and became confirmed cases. 1,037 asymptomatic patients have been released from medical observation.
Research published by Chinese scientists including Zhong Nanshan, the senior adviser for the government, said the median incubation period for COVID-19 was 3 days (with a range of 0-24 days). Commonly accepted period for quarantine is 14 days. https://bit.ly/2yN6AVN 
It's not a like for like and it's not clear when those who ended up developed symptoms were first reported as asymptomatic cases. But the very crude calculation for purely illustrative purposes of 57/657 nationally is 8.7% and 2/303 is 0.6%.
The fact that there are so few asymptomatic patients reported to have developed symptoms in Hubei and mainland China, in comparison to how many new asymptomatic cases have been reported so far, raises some questions.
Neither the NHC nor Hubei has provided cumulative statistics on asymptomatic cases found to date or the number of such patients later developing symptoms. So there is a limit to what we can discern from public disclosures.
Data published on April 1 by Hubei, for example, the province reported 47 new asymptomatic cases, 1 asymptomatic patient who developed symptoms and 289 asymptomatic patients who were released from medical observation. 982 asymptomatic cases were being monitored at the time.
That probably means there were 1,225 under medical observation in Hubei as of March 30.

From March 31 and April 8, Hubei released 852 asymptomatic patients from observation. Noting again that there were only 2 cases of asymptomatic patients developing symptoms in this window
I am just using official data and have no knowledge of what's happening on the ground. Straightforward reasons could be:

-Patients are being pumped with enough drugs/treatment to keep symptoms from emerging
-It's just taking time for the symptoms to emerge

...
-Incubation period may be longer than 14 days that we generally expect (there have been some cases of this)
-Patients are not being tested correctly or test kits are still not very accurate
...
Some will also look at this thread and accuse Hubei/China of doctoring the data. I have no evidence on hand to prove such an accusation and it would be irresponsible for me to say so without evidence - especially given my current occupation.
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