There are a number of differences between award and revenue fare searches. Among other differences, DL only generally maintains revenue fare filings and will sell you revenue tickets for routes that either begin or end in the Americas region or US territories. Just because DL has codeshare flight numbers on partner flights doesn't mean they can sell you a ticket on those flights if it does not begin or end in Americas/US territories or if it is not part of an itin that does so (fares are priced on an O&D basis, not hop-by-hop). In addition to no fare filings, cabotage issues may also be a factor (they can't sell revenue fares for an itin that both begins and ends within Canada, for example -- you'd have to book them on separate tickets). Meanwhile, award bookings are not subject to such limitations (note that when booking awards as partners, it will always book as a partner flight number even if there are DL codeshare numbers on flights).

Skymiles awards to/from US/Canada now have a number of similarities with revenue fares. They duplicate a lot of the revenue fare filings with award "fares" on routes which includes largely duping the fare rules restrictions (advance purchase, roundtrip booking, day of travel, etc) -- it's not one-to-one, but it's close enough that award mileage rates mostly correlate with revenue fare prices. They have also duplicated the revenue fare classes with award fare classes on DL metal flights. While bucket inventory availability between the two is not always identical, it's generally pretty close. However, they don't always duplicate routing rules and married segment inventory availabilty from revenue fares to award fares (many have noticed cases where there is no married inventory on a particular route for revenue fares, but there is still married inventory for awards and you can still book award fares on the routing).

Whatever the delta.com bug that is currently affecting revenue fare searches on FWA-HND, it is not impacting Skymiles award searches on route. The revenue fare search bug on delta.com doesn't look to have anything to do with fare filings or married segment inventory (other fare search engines can find DL fare availabilty just fine). With revenue fares going for $2K range roundtrip for Main on this route for summer travel, award fares are in the 200K mileage range roundtrip in Main for this time period (before Amex 15% discount), as expected (US/Canada awards are generally in 1.0 - 1.2 CPM range before Amex discount).