I've gotten to November 2601 and I haven't gotten the codex yet.
I've never had trouble getting it before so I don't think I've forgotten any obvious steps to get it and I've gotten the spacious hull and the bio-plasma gun.
I believe I'm just waiting for the anomaly to stabilise, but I've been waiting about 6 months now.
Edit - I accidentally added the wrong save, this is now the correct save.