When you started your tax return for 2018 did you "Start a new return" or "Transfer into a new 2018 return"? If you started a new return you would have to manually enter it. If you transferred to a new return, did the time limit end for carrying it forward? That might be why.
From what I understand that Notice Of Assessment should have shown a carry forward. I understand you as a question I needed answered wasn't answered from Turbo Tax but rather I obtained information through this community forum.