ID:2127048
 
Not a bug
BYOND Version:511.1350
Operating System:Windows 10 Home 64-bit
Web Browser:Chrome 52.0.2743.82
Applies to:Dream Daemon
Status: Not a bug

This is not a bug. It may be an incorrect use of syntax or a limitation in the software. For further discussion on the matter, please consult the BYOND forums.
See title.

L2 uses "Axis 2 +" and R2 uses "Axis 2 -", and they seem cancel each other out when they're both pressed. This shouldn't happen.
Lummox JR resolved issue (Not a bug)
This is intentional on Microsoft's part. They built the L2 and R2 buttons to share an axis when read by DirectInput. Other gamepads don't have this issue. In fact, the controller that reads as "Controller (Xbox One For Windows)" maps L2 and R2 as separate axes like it should, so a number of newer controllers apparently don't have this issue.

[edit]
Actually now I'm confused, because you're the one who provided the setup for that controller. According to the original setup you provided, both axes should work independently.

Controller (Xbox One For Windows)
buttons = Face1,Face2,Face3,Face4,L1,R1,Select,Start,L3,R3
axes = 0,1,3,4
axisbuttons = ,,L2,,,R2

That setup means L2 is axis 2 +, and R2 is axis 5 +.
In response to Lummox JR
I forgot to mention, the binding changed since the previous build. It's now as I said it is in the OP. I'm guessing it's because of the change for Xbox 360 controllers.

Even if it's intentional by Microsoft that L2 and R2 use the same axis, it doesn't mean this isn't a bug. Obviously, the triggers can be detected separately (by XInput).

If it's considered "not a bug" simply because only DirectInput is officially supported, would you consider adding XInput support? BYOND games are basically Microsoft-exclusive anyway...
I'd consider XInput down the road possibly; it may take some work to get it working.

I'm not sure how or why your setup changed, though. Your gamepad should be reading the same as it did before, unless there's some kind of mode switch on it that you may have changed that would have changed the name.
In response to Lummox JR
I don't know. The triggers weren't responding how they used to, so I went into Gamepad Setup and redid all the things (which works perfectly now, by the way, by actually responding to my inputs) and the triggers changed.

There's no mode switch, it's the stock Xbox One controller.
What does your updated joysticks.txt look like?
In response to Lummox JR
Controller (Xbox One For Windows)
buttons = Face1,Face2,Face3,Face4,L1,R1,Select,Start,L3,R3,,,Up,Down,Left,Right
axes = 0,1,3,4
axisbuttons = ,,R2+L2
Have you tried changing the setup to this?

axisbuttons = ,,L2,,R2+

That will map axis 5 - to R2, per your old configuration. Or is axis 5 no longer showing up?
In response to Lummox JR
I'm using 511.1351 now.

I tried all 5 axes, positive and negative, and the right trigger only responds to "2 -".

Regardless of what axis right-trigger is set to, pulling it cancels out the left-trigger.