Odds are your cable is mis adjusted and simply not pulling the internal clutch all the way to first.
SA hubs use the same internal power path in 1st and 2nd, with a ratchet that allows 2nd to overrun 1st (the slow clicking). When the cable is pulled out a bit more, a part of the sliding clutch disengages the 2nd gear ratchet allowing the hub to turn at the lower speed of 1st.
Shift to 1st and forgetting the lever for the moment, pull the cable as far as you can and see if it has more to go. If so, that's your problem, and you need to tighten (shorten) the cable a bit. If there's no more thread on the adjuster, back off or disconnect the adjusting barrel, loosen the cable stop clamp and slide it up the stay about 1cm and tighten. Then attach the cable and adjust so it pulls all the way out less about 1/32" when in first.
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FB
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