If there is a significant amount of time left on the engagement timer and the fleets are in reasonably close proximity, I would suggest that the "no contact between fleets" scenario ending condition should not trigger.
There is a reasonable possibility that my destroyer force would find this convoy with slightly more time allowed for a search - they're only separated by 20nmi, so if I turned my destroyers West for the next leg of the search there is a reasonable chance that I would find the convoy well before the scenario ends. Additionally, the convoy is currently overrunning my submarine I-7, so I might very well have received a contact report indicating the convoy's position had the scenario gone on even slightly longer.
I doubt, if "no contact" fast ending should be here at all. Even if fleets miss each other, you may find the enemy after some searching. If you still miss them, "fleets too far" ending is available. And convoy mission sometimes is impossible now - if your force has slow ships and angled at wrong direction, you may have too little time after course/speed is unlocked. I suggest to rework whole mission type into something like "coastal raid" - plenty of time, large distance, several possible positions of convoy and more AI squadrons - both friendly and enemy. And no locks/fast endings!