FIX: Input devices sometimes marked as disabled on reconnect

Assets/Tests/InputSystem/CoreTests_Devices.cs

@@ -1501,6 +1501,52 @@ public void Devices_WhenRetainedOnDisconnectedList_CanBeReconnected(string devic
         Assert.That(InputSystem.disconnectedDevices, Is.Empty);
     }
 
+    // https://fogbugz.unity3d.com/f/cases/1404320
+    [Test]
+    [Category("Devices")]
+    public void Devices_CanReconnectDevice_WhenDisconnectedWhileAppIsOutOfFocus()
+    {
+        runtime.runInBackground = true;
+
+        var deviceDesc = new InputDeviceDescription
+        {
+            deviceClass = "Gamepad",
+            product = "TestDevice",
+            serial = "1234"
+        };
+
+        var deviceId = runtime.ReportNewInputDevice(deviceDesc);
+        InputSystem.Update();
+
+        var device = InputSystem.GetDeviceById(deviceId);
+        Assert.That(device, Is.Not.Null);
+
+        // Loose focus.
+        runtime.PlayerFocusLost();
+        InputSystem.Update();
+
+        // Disconnect.
+        var inputEvent = DeviceRemoveEvent.Create(deviceId, runtime.currentTime);
+        InputSystem.QueueEvent(ref inputEvent);
+        InputSystem.Update();
+
+        Assert.That(InputSystem.disconnectedDevices, Is.EquivalentTo(new[] { device }));
+        Assert.That(InputSystem.devices, Is.Empty);
+
+        // Regain focus.
+        runtime.PlayerFocusGained();
+        InputSystem.Update();
+
+        var newDeviceId = runtime.ReportNewInputDevice(deviceDesc);
+        InputSystem.Update();
+
+        var newDevice = InputSystem.GetDeviceById(newDeviceId);
+        Assert.That(newDevice, Is.SameAs(device));
+
+        Assert.That(device.added, Is.True);
+        Assert.That(device.enabled, Is.True);
+    }
+
     [Test]
     [Category("Devices")]
     public void Devices_WhenRemoved_DoNotEmergeOnUnsupportedList()

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -59,6 +59,7 @@ however, it has to be formatted properly to pass verification tests.
 - Fixed missing tooltips in PlayerInputManagerEditor for the Player Limit and Fixed Splitscreen sizes labels ([case 1396945](https://issuetracker.unity3d.com/issues/player-input-manager-pops-up-placeholder-text-when-hovering-over-it)).
 - Fixed DualShock 4 controllers not working in some scenarios by adding support for extended mode HID reports ([case 1281633](https://issuetracker.unity3d.com/issues/input-system-dualshock4-controller-returns-random-input-values-when-connected-via-bluetooth-while-steam-is-running), case 1409867).
 - Fixed `BackgroundBehavior.IgnoreFocus` having no effect when `Application.runInBackground` was false ([case 1400456](https://issuetracker.unity3d.com/issues/xr-head-tracking-lost-when-lost-focus-with-action-based-trackedposedriver-on-android)).
+- Fixed an issue where a device was left disabled when it was disconnected while an application was out-of-focus and then re-connected when in-focus (case 1404320).
 
 #### Actions
 

Packages/com.unity.inputsystem/InputSystem/InputManager.cs

@@ -2248,6 +2248,7 @@ private void OnNativeDeviceDiscovered(int deviceId, string deviceDescriptor)
                     device.m_DeviceId = deviceId;
                     device.m_DeviceFlags |= InputDevice.DeviceFlags.Native;
                     device.m_DeviceFlags &= ~InputDevice.DeviceFlags.DisabledInFrontend;
+                    device.m_DeviceFlags &= ~InputDevice.DeviceFlags.DisabledWhileInBackground;
                     device.m_DeviceFlags &= ~InputDevice.DeviceFlags.DisabledStateHasBeenQueriedFromRuntime;
 
                     AddDevice(device);