The transmitter will output brakes if you use drag brake on it. Therefore, if your ESC has reverse enabled, it'll eventually go into reverse. You can't do it properly with the transmitter if you have reverse enabled.

I used to use my 3PJS to trim it so the drag brake was correct, then use "throttle acceleration" or 'Th.Acc' to make it so when I barely pull the trigger, I'd get throttle response.

Just as an FYI, some ESCs may freak out and not arm if set up like this, so you may have to trim it to neutral when you power up, then trim it back after it arms. Just make sure to count the clicks so you know how many to go back.

If you have an ESC that has a 'drag brake' feature, it's much easier to adjust on the ESC.

-Eric