"In my free time, I like to read"
Translation:In meiner Freizeit lese ich gern
why is 'Ich lese gerne in meiner Freizeit' not acceptible?
Because the Pearson editor who added this sentence made a mistake -- they included Ich lese ich gerne in meiner Freizeit as an option instead of the correct Ich lese gerne in meiner Freizeit.
That cooperation was short-lived and their sentences were never supposed to show up in the public course, but here we are. I don't think the Pearson editors ever looked at error reports or read sentence discussions, so those errors remain -- the responsibility of the volunteer course contributors and, since April 2021, the paid freelance course contributors.
And with the hundreds of thousands of reports to go through, it will probably take the current course contributors years to get to this one.
Until then, feel free to keep reporting Ich lese gerne in meiner Freizeit as an acceptable translation, but don't bother posting about it here in the sentence discussion, which is mainly read by other learners who can't do anything about it.
Your sentence is completely fine.
One of the accepted sentences is Ich lese ich gerne in meiner Freizeit, which is (unfortunately) nonsense.
This sentence was added by Pearson contributors; see https://forum.duolingo.com/comment/24066422 for an announcement of the effect this has had. Many of their sentences are fine but some (such as this one) contain mistakes.