There is a block missing in your new set?
You can report it to cobi, they will help you solve the problem. First, check whether the missing block did not get lost in the bag, the carton or was not covered by another block.
Maybe it was used in the previous assembly step? Sometimes it happens. If it is not there, fill in the registration form.
Here you can report your problem:
EN: https://cobi.pl/en/customer-service/missing-blocks/