Quick answer: Set the input mode to UI or game-and-UI, give the widget focus, and set its visibility to a hit-testable value.
UMG widget input not working is input mode, focus, or visibility. Here is how to fix it.
How to fix it
1. Set the input mode
If the player controller's input mode is game-only, UI widgets get no mouse input. Set it to UI Only or Game And UI (with the mouse shown) so the widget receives clicks.
2. Give the widget focus
Keyboard and navigation input go to the focused widget. Set focus to the widget (or a control in it) so it receives key and navigation input, especially for gamepad menu navigation.
3. Set hit-testable visibility
A widget with visibility set to Hit Test Invisible or Collapsed does not receive input. Set interactive widgets to Visible so they are hit-testable and can receive clicks.
Catching the ones you can't reproduce
The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.
Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.
This is where a tool like Bugnet earns its place. Its SDK captures every Unreal Engine error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.
Reproduce it once with full context and the fix writes itself. The hunt is the expensive part.