The earlier drop to amber in cold weather is normal, nothing to worry about since all batteries operate best around 20 to 30 degrees C and lose efficency as that temperature reduces.
Your pedelec switch inside the meter is a single pole switch with two wires going to it, black and yellow usually. When joined by switching, the throttle mode is on, so it sounds as though either the rocker switch is faulty or one of the wires is disconnected or open circuit. leaving you with pedelec only.
There are long thin cross head screws in the underside of the meter which allow you to part the meter box so you can check the wiring to the rocker switch or remake the connections to it. As you part the meter box, one of the nuts used for securing the handlebar clamp will probably fall out of it's recess, make sure you don't lose it and make sure you include it as you clamp the box back together again.
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