So I think I've found the error, or at least a workaround to deal with it. The Carry Fwd form is reporting the 2023 RRSP Limit in the line near the bottom "Unused RRSP contributions". When the value there is overidden and the proper value (in our case $0) is inserted, the correct value of 2023's RRSP contribution appears in line 20800 of the T1.
Since this is appearing in form Carry Fwd, I can only think that TT is importing from last year's return improperly.
Nuts, our refund just went down by almost $20,000.
