verification code can't be remembered after browser close even if "remember in browser" gets checked

I'm trying asp.net identity 2.0.

with "remember in browser" checked in verification code page, click "Veirfy" with correct code, I can log in.

and before closing the browser, re-login doesn't ask for verification code.

but after closing the browser and reopen the browser, login always asks for verification code, and the code generated before becomes invalid, I have to generate a new one.

during debugging, I noticed AuthenticationManager.TwoFactorBrowserRememberedAsync return false.

how come?

Thanks,