“There is little or no evidence that the attack on Otranto was the intended start of a full-scale formal invasion of Italy.”
Who are you reading? Might want to ask the Knight of Malta about that one...
The Otranto attack was a large-scale raid. If fully successful, it might very well have been followed up with an invasion.
But no attempt was made to reinforce the Ottoman garrison, probably because the Sultan died and as usual there was squabbling over the succession.
No further attempt was made to invade the Italian mainland, other than coastal raids to plunder and capture slaves.