Hi nda,
Thanks for your updated information.
I checked your SDK2.9.1 for MIMXRT1020, in fact it is used for azuarertos, not the freertos.
So, if you run the freertos code, I suggest you download the SDK2.9.0, and delete the 2.9.1 in installed SDKs, add the SDK2.9.0,freertos version:
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Wish it helps you!
Best Regards,
Kerry