"Your child is drinking milk."
Translation:Wasze dziecko pije mleko.
"twój dziecko" is incorrect. "dziecko" is neuter and it should be "twoje" https://pl.wiktionary.org/wiki/Aneks:J%C4%99zyk_polski_-_zaimki#m.C3.B3j.2C_tw.C3.B3j.2C_sw.C3.B3j
This is a system fault. I wrote "twoj dziecko". OK, that was wrong, I should have written "twojE dziecko". But the machine corrected me to PANSTWO dziecko. If it doesn't say whether the "you" intended is singular or plural, formal or informal, users should not be marked wrong for guessing the wrong one.