"Buying power" works differently in paper trading vs live account?

Quick question - I have been up and running with a paper account and it’s working great. I’m trying to get my live account to work basically the same way but am running up against a difference in the way buying power is reported in each environment.

First, some context for the trades I am making -

No day trades
Rotating entire portfolio in and out of different symbols (max 1 trade per day)
“Limited margin” only - I want to be able to trade with unsettled funds, but don’t care about leverage or shorting
Symbols supporting fractional orders, deploying my whole account balance on each trade

On the paper account, “buying power” just gives me the value I am looking for. On the live account, however, it gives me 2X leverage on my account equity. My orders are also rejected due to insufficient buying power when I use this value as my buy amount.

What explains the discrepancy between paper and live account behaviors? Is there a single value I can use for both environments that will have the desired effect? I was thinking of trying “non-marginable buying power,” but I want to also include unsettled funds which I think technically is considered margin.

Thanks!