"Instead my mother recognized him right away."
Translation:Invece mia madre lo ha riconosciuto subito.
Bio, that is what my grammar book says:
lo, la, mi, ti, vi may drop their final vowel before another vowel or the letter h. Ci may drop the -i only before e or i.
Roberto? L'ho visto ieri sera.
Robert? I saw him last night.
taken from: Italian Verbs and Essentials of Grammar' Carlo Graziano, 1987, p. 155
DL rejected: " Invece mia madre l'ha riconosciuto subito" . This is indeed a glaring mistake, in my view, unless for reasons of oral emphasis the preferred expression is with "lo". Even then it should not be marked wrong unless there are reasons unknown to non Italians.
How about this: My little brother often tried to sneak into the house in different disguises and fool our mother. But instead, she was always recognizing him right away. Therefore: "lo riconosceva subito". This was a game our family played for years. So why would this not be accepted, other than Duo's penchant for being a little narrow at times.
Interesting conversation. You're correct that in English I would normally say, "She always recognized him right away". And I would argue (though admittedly far from a grammatical expert in Italian or English), that this was an ongoing action, now ended. For example, if I tried to say in English, "As child, I used to ride horses", the Italian version would most likely be, "Da bambino andavo a cavallo." This was something I did (actually never!