You're getting a signal, and it appears to be from the correct satellite, but it is a vertical transponder, and you are looking for horizontal ones. LNB power set to 13/18 should mean it is switching correctly.
Some of the older Sky LNBs are failing, but given it was working OK a few weeks ago, this is less likely. As they go, the LO frequency can drift slightly - to test this, try changing the 10750 LNB frequency to 10752 or 10748 and try another scan. If this works, it means the LNB is on it's last legs and should be replaced.