The key is that two of its three carriers, namely the "Invincible" and "Athena" were sent into dry dock shortly after returning to port. The reason was that their propulsion systems malfunctioned and had to be docked for repairs, with the "Athena" also needing two propellers replaced. However, there is reason to believe that these two carriers were attacked outside the port and hit by torpedoes, necessitating dry dock repairs upon returning.
As for the unscathed "Royal Ark," it has remained in the harbor.
Additionally, the Bulan Royal Navy only admitted in early October that it hadn't found the submarine fleet that conducted the raid, and the previously claimed "sinks" were actually suspected targets.
Those two submarines were indeed not sunk and had slipped away before the successful raid.
