In the US, all deep discount brokers that I know will charge an overnight fee for an overnight open position.
Usually, the charge is about an annualized rate of 4 to 12% depending of the broker, multiplied by the total exchange minimum maintenance margin requirement (do the maths!).
Tradestation would charge a "fixed overnight fee" of $0.10 per contract.
I think NFA charge all Future brokers $0.01 overnight fee, except for exchange members.
If you don't want that kind of fees, you need to find a "fixed pricing" Broker.
They are great as long as you do not carry futures overnight. I was with them for years, but I swing futures positions and they put in an overnight charge. I had over seven figures with them and it became prohibitive. Had to go. Had no problem wiring money out. Other than that overnight deal breaker,I liked them very much.
From Advantage, where did you switch to?
I would check on that waiving overnight interest at advantage. It seemed pretty solid just a few months ago when they chased me and another bigger player than myself.