This is described in MAW2 page 644: "11 B-24Ds from 344th and 345th BS, 98th BG attacked between 1920 and 1935 hrs a convoy of "3 merchants" SW Crete, claiming four hits, two probale hits and 11 near misses, resulting in two ships probably sunk. 3 fighters intercepted them and the B-24D 41-11763 of 345th BS that was straggling was shot down off Gavdos Island (2 POW, 7 MIA). Pvt Tom F Hattaway, the rear gunner of 41-11806 of 345th BS, claimed a German fighter (Bf 109 or 110) probably shot down.
Two pilots of III./ZG 26 (a Bf 110 unit) claimed B-24s, Uffz Fritz Lauff at 1820 hrs (German time) and Obfw Walter Weiss at 1830 hrs SW Gavdos. No German aircraft was lost according to the book.
As for the convoy target, I think it was the "sportivo" convoy. The Kriegsmarine Naval Staff KTB reports only this convot attacked in the area (the Italian tanker Pozarica was torpedoed that day S of Corfu by Malta-based RAF aircraft). The ships suffered no damage.
According to the links below it was composed of Italian cargos Sportivo and Davide Bianchi and tanker Stige, escorted by four warships Turbine, Lince, Hermes and S 41. S 41 was sunk in November 1941 in Channel so that part is false. Hermes, a former Greek destroyer taken over by the Germans, could have been there but in the above cited KTB is reported to have assisted U-83 on the 18th and is not cited on the 21st.
The onlise story of some of the ships involved, but with few details:
https://conlapelleappesaaunchiodo.bl...5/turbine.html (listing the ship discussed above)
https://conlapelleappesaaunchiodo.bl.../sportivo.html (same ship list)
https://conlapelleappesaaunchiodo.bl.../09/lince.html (no mention of this convoy)