Why does Turbo Tax present error when the date I became a resident of foreign country is NOT in 2021?

Hello:

I am an U.S. citizen and California resident who moved to Hong Kong for my job since September 2020.  In answering the question below related to State of Residence for 2021 tax return, I wanted to answer 9/1/2020 because that was when I started working abroad.  Nevertheless, Turbo Tax presents an error and requires a date in 2021.  Any idea on why the error and is it ok if I put 1/1/2021 just to get pass that error?  Thanks much!!

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