A couple months ago, I booked an Air Canada Latitude (Flexible Economy, B fare class) ticket for BER-FRA-YUL-YOW return, with the BER-FRA and FRA-BER operated by LH as an AC codeshare.

At the time, I was able to select and confirm seats for the LH legs via the LH app / website with no additional charge (it said "included in fare").

Now that my BER-FRA flight is only 4 days away, I noticed I have lost my previously selected seat, and selecting any seat will result in a charge. For the FRA-BER let in August, the previously selected seat is still there.

1) Should I ever have been able to make these advanced seat selections in the first place?

2) Will I lose my seat on the return as well?

3) Will I be able to select a seat for free at check-in?