Quick answer: Unreal Enhanced Input modifier (deadzone, scale) applied twice on the action value? You added the modifier on both the Input Mapping Context and the Action — pick one.
Stick input registers as 4x the expected magnitude. A Scalar modifier is on the IMC’s mapping and on the Input Action’s modifiers list.
Two Modifier Slots
Modifiers exist on the Input Action (always applied) and on the IMC mapping (applied only for that binding). Configuring both stacks them — deadzones become huge dead zones, scales compound.
Centralize Modifiers
For per-action behavior (always scale, always deadzone), put modifiers on the Action. For per-input-source overrides (e.g. invert Y on a specific controller), put them on the IMC mapping.
Order Matters
Modifiers run top to bottom in the list. A swizzle after a scalar gives different output than scalar after swizzle — arrange in the order you want.
Verifying
The action value matches the expected formula at all input magnitudes. Sticks, triggers, and buttons behave predictably.
“Modifiers stack across IMC + Action. Configure each spot only when it’s the right scope.”
Document each Action’s modifier list in the asset description — otherwise it’s pure tribal knowledge and you’ll re-debug this in six months.