My 2012 Expedition won't shift between 2nd and 3rd gear sometimes

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My 2012 Expedition won't shift to between 2nd and 3rd gear sometimes. The Rpms would run high. Turning the car off and back on usually takes care of the problem. Usually this happens about once a week. Transmission fluid changed recently but the problem is still there. Took it to the dealer, and they could not find a the problems. I also took it to a transmission "specialist", he hooked it up to computer and could not find any problems. What should/can I do?