That's going to be almost entirely owner occupied stuff where single family houses are selling for above $250k and things of that nature. 

I have found a lot of success in the past and not so far past in purchasing lots, building an "affordable" home and selling it as a spec home. 

So they are selling 1/2 a duplex and someone owns the other half?

As rates drop further and the spring/summer selling season will push values higher. 

Flipper is going to sell the houses to the highest bidder.

I'd rent in Jacksonville for a minute and keep your current and run it as an STR vs. selling.

So someone toes up a property via a purchase contract and then sells that contract to a third party.  

Because I have another investor on this project and I have to pay him out of the profit, and also is it possible to get a pre approval letter before selling my investment property because it throws off my debt to income ratio, but it's an investment property that is meant to be sold.

You could choose to not renew their lease and start construction now with a detached ADU and a JADU attached to the original house, then in 3 years go for the lot split.I went this route because the resulting 2 lots will sell for much more than 1 lot with 4 units.

The listing has been live for 180 days and has yet to sell through my real estate agents.