"Ona" is not in the list of words given
I typed "Začíná se o to zajímat." It was also counted correct.
Interesting how when you specify the pronoun the verb 'gets forced' to move backward due to the priority rules.
It is interesting that the Cz version here differs form the 'correct' answer shown in the lesson! (As they say' there is more than one way to skin a cat'!)