OK, escalation took more than 1 hour on the phone, but it did resolve the issue. For anyone else in the same boat:
1) I think CRA does not actually receive those turbotax forms that include the date range, so in some sense this does not matter. (This was my own conclusion.)
2) I made a mistake on turbotax: each claim has a date field, which by default was 12/31/2023. Once I started to put at least one claim to 2022, suddenly I could choose a different claim period! (This did NOT work when all the claims were in early 2023, for some reason.)
3) There are definitely bugs in the turbotax program: it should be possible to choose the claim period independent of the claim dates, but there should be a warning then. Even worse: even once I could change the claim period, one of my claims accidentally was outside of the period and my deduction suddenly decreased. Without warning!
