This put us in a significant disadvantage on selling, buyer has to have 20% down and buyer needs to use a Non QM lender too instead of a standard back or broker...

I would probably focus on three things.  1) filling the vacancy for as close to the old rent as possible (to help with refinancing or selling 2) refinance it and talk to a few different banks/brokers.  3) If all else fails, list it and 1031 into another project. 

Cash flowing at 5% down was possible about 3 years ago—but that ship may have since sailed.Now, you’re left with two options: you can either pony up more cash per deal, or you can potentially look out of state for markets with more favorable rent-to-price ratios.Or…you can wait for rates to decline, but I don’t know how much a 100 or 150 basis point rate cut in the next year will really move the needle.That said, some firms (usually new construction companies, turnkey providers, etc.) will enter into forward commitments with lenders at institutional rates and then pass cost interest rate savings onto end buyers to entice them to purchase a property.

Banks foreclose on properties when owners fail to pay their mortgages.

If lenders would consider a 2-3% buyers agent commission as part of the purchase price and LTV based on this (contract price + buyers agent commission) we can end this Byzantine step of the buyer’s agent having a separate agreement executed with the seller for the seller to offer to cover the buyers agent commission.  

The other funny one is when a first time buyer comes to me with their fha loan and says they want to find a "deal".

its creating some friction with brokers that are representing buyers  Listing agents no change.the commish is becoming a negotiation just like a home inspection..

The business agreement would act similarly if an STR manager fails to pay, but that kind of an agreement may be less familiar than a long-term lease to a long-term lessor.

Solid 2-4 unit properties are so scarce in these areas (~21 sales in last 12 mo between the 2), the market simply doesn't allow a buyer with a low downpayment to enjoy any "income" out of the gate.

A seller cannot “cancel” a contract that has been prepared properly unless the buyer breaches its terms.