It takes time to integrate two different reservation platforms. Getting the PNRs, SM# and elite status to transfer over was a good step in the right direction. It is unrealistic to expect that everything between the two entities will be completely seamless so quickly after legal merger completion.
When ever two very large companies merge this is precisely how things go and DL/NW are right on track compared to other similar sized companies merging in any industry.
I used to work for a very large telecommunications carrier and years after a merger with another large carrier they still couldn't look into each others systems. That was a failure as it shouldn't take 10 years, but for DL/NW they are progressing nominally.