Strange banding on first layer/skin
i'd say your extruder driver and/or motor is overheated - really 

according to your description - when you've printed other things it was fine but this is the first with such big "flat" area

usually extruder motor works for some time then stops and starts and so on and again so it has some time when driver cools down but here it runs constantly for relatively long time

this overheats the driver and/or motor then is starts to clicks as there is not enough current delivered to the motor

what can you do?


try to take the cover off
check the driver temperature (use electronic thermometer as it can be even 100C)
try to cool it with some kind of fan while running the same printout


if the diagnosis is fine - you are at home and now you know what to do ;)



the one described as E is the one to check and cool down