If the F cabin is not fully booked, 1A/1K are released approximately 72 hours before the flight (before OLCI opens) if it is not already assigned to the highest tier JMB members.
In cases where the F cabin is fully booked and some passengers do not have seat assignments, any remaining seats (including 1A/1K) automatically gets blocked (and then automatically assigned to them with no possibility to move when checking in).
Use "manage booking" to change your seat and not OLCI.