Sorry to hear that! We personally had the same result last night, we had sent out to only sector 5 to try to discover 7 but were unsuccessful. We got a substandard rating which I think I’ve seen other people get AND still discover areas. Upon closer review the line about violent turbulence says “Airship surveillance levels unaffected,
but EXPLORATORY CAPABILITIES may be significantly hindered.” so maybe that has something to do with it. We sent it back out on the route to 5 -> 6 so I'll know some more this evening. We haven't been able to complete our invincible forecastle yet but I'm thinking that we might need to lean hard on it and get it done just to advance :-/ Banzai, we may have found one of the walls

Will keep updating with findings.
Looking at the spreadsheet, it appears that all entries that have found new sectors (so far) have mostly had satisfactory end results(except possibly line 5) from the Sector of interest AND have seen violent and high winds, with high winds being the 2nd entry before discovery of the new sector, so perhaps slight hindrance still allows for discovery of new sectors while significant hindrance does not?