I have just tried the Manage My Booking facility and it seemed to be working normally.
It has been stated on this forum many times that the exit rows are only available upon request at check in. So are bulkhead seats with baby bassinet fittings.
For safety reasons, exit row seats are only available to able bodied passengers who are prepared to assist with the opening of the emergency door if necessary.
Not even PC Elite members have the privilege of pre-selecting them.