As ambaloch87 said, IPENZ registration and membership are two different things. Did you managed to get KA01 initially before the ITA submission ?
As you said you have your EA positive assessment, may I know what is your ANZSCO ? and from which university did you obtain your bachelor/master's degree ?
I am still trying to understand that with your EA positive assessment, you should have no problem in getting the KA01 assessment, both registration and membership. Because in my case, I have even clarified the same with my IQA assessment evaluator.