Frontier Airlines EarlyReturns - Choice Award

Are there any circumstances when a domestic one-way award booking, with a search engine routing, would require 45,000 miles?

I thought that the Standard Award was 12,500, Choice was 22,500 and Last Seat Available Award was 25,000. However, in searching PHX-MKE award availability, the following was displayed:

Lowest Award Option
45,000 miles - Choice Award
Flight F9 0126
Departs 09:40 AM
Arrives 03:54 PM
Airports PHX-DFW
Layover: 1h 6m

Flight F9 1784
Departs 05:00 PM
Arrives 07:16 PM
Airports DFW-MKE
Operated by Republic Airlines
Total: 7h 36m


It almost looks like this routing was treated as two separate one-way Choice Awards, instead of a connection.

Treating it as two awards would make sense, since it's a two-stop with the second stop being at a "spoke." Out of curiosity, why not PHX-DEN-MKE?