When unlocking FPS in Viewport it defaults to 120 instead of potential max FPS. If you do this during Launch the 't.MaxFPS 0' or 't.MaxFPS -1' commands unlock the FPS to the max the GPU allows in the Viewport. When testing in Editor/PIE the commands set FPS to 120 and when in Launch the FPS was unlocked to 250+ FPS.
Results: FPS defaults back to 120 instead of being unlocked
Expected: FPS is unlocked to potential max FPS. In test case this was 250+
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