A method and apparatus are disclosed. In an example from the perspective of a User Equipment (UE), a Slot Format Indication (SFI) is received within a first Channel Occupancy Time (COT) of a serving cell. The SFI is indicative of one or more slot formats of one or more slots of the serving cell. A first signal indicative of an ending position of the first COT is received. A beginning of at least one slot of the one or more slots is after the ending position. The UE determines whether to apply a slot format, of a slot of the one or more slots, to the slot based upon whether the slot is within the first COT, wherein the slot format of the slot is indicated by the SFI.