STABLE version -- 5.0.1002.354

[Admin]

No settings, no extensions
It doesn't go in at the initial state,

https://signinssl.gmarket.co.kr/login/lo...t.co.kr%2F

Please test if you can connect 64-bit
32-bit is connect ok

https://browserleaks.com/tls

command prompt = inetcpl.cpl,6
security option
ssl3.0 x
tls1.0 o
tls1.1 o
tls1.2 0
tls1.3 x

64bit gmarket login
ok

Thanks, I can reproduce this issue sometimes(not stable).
Seems it is more likely network or website issue.
If you have VPN you can try using it, or try changing your DNS servers to 8.8.8.8 and 8.8.4.4 and then run 
ipconfig /flushdns
in cmd.exe