Troubleshooting

Debug interaction issues by isolating the failed stage.

Interaction Engine has several independent stages: focus acquisition, prompt display, input prediction, server validation, confirmed execution, runtime state replication, widget updates, and persistence. When something fails, identify the first stage that stops working before changing unrelated settings.

Useful debug commands

Enable only the categories related to the problem you are investigating. Disable them again after testing to keep the Output Log readable.

Prompt never appears

• Confirm that the player pawn or character owns an InteractionInteractorComponent.
• Confirm that the target actor owns an InteractionInteractableComponent, or that foliage is configured in the interactor's foliage database/data table.
• Confirm that the player is within TraceDistance, NearbyDetectionRadius, and the target's widget visibility distance.
• Check collision channels, object responses, and line-of-sight rules used by the selected trace method.
• If using angle-based selection, review ViewAngleDegrees, camera direction, and target bounds.
• Enable ie.Debug.Focus 1 and verify whether the target is found, rejected, or never considered.

Prompt appears, but the interaction does not execute

• Confirm that the input calls StartInteract, StopInteract, or SendHit on the same actor that owns the interactor component.
• Confirm that the focused slot is enabled, not blocked, not on cooldown, and accepts the current interaction type.
• Check CanInteractSlotWithReason or rejection logs to see why the slot is denied.
• For hold interactions, verify that input press calls start and input release calls stop.
• For damage or multi-hit interactions, verify the active damage type and the slot's required damage type.
• In multiplayer, bind gameplay to confirmed events, not only local prediction events.

Interaction works on the server but not on the client

This usually means local prediction happened, but the server rejected the interaction or the client is listening to the wrong event. Client-side visuals may react immediately, but gameplay results should come from confirmed events.

• Use OnInteractionPredicted_LocalOnly for immediate local feedback only.
• Use OnInteractionStarted_Confirmed, OnInteractionCompleted_Confirmed, and OnInteractionCancelled_Confirmed for authoritative gameplay.
• Listen to OnInteractionRejected_LocalOnly to detect failed client attempts.
• Enable ie.Debug.Net 1, ie.Debug.Validation 1, and ie.Debug.Transaction 1.
• Check whether the server's trace/validation distance, line of sight, focused target, and focused slot match the client expectation.

Progress bar does not update

• Use InteractionFocusWidgetBase for the main prompt widget.
• Use InteractionRowWidgetBase for each displayed slot row.
• Confirm that each row has the correct SlotID.
• Confirm that bAutoDiscoverRows or manual RegisterInteractionRow setup is working.
• Confirm that bAutoUpdateRegisteredRows is enabled if you expect automatic progress updates.
• Bind to On Interaction Row Progress Updated on the row widget when driving a custom progress bar.

Input glyph is missing or wrong

• Prefer setting InputAction on the slot display settings. Use KeyLabel only as fallback or legacy text.
• Confirm that the input action is mapped in the active Enhanced Input mapping context.
• For gamepads, set the desired style with Set Gamepad Glyph Style, or configure DefaultGamepadFallback.
• Check whether the glyph database contains an entry for the resolved key and device/style.
• Enable ie.Debug.Glyph 1 to inspect resolved device type, key, and fallback behavior.

Foliage prompt appears, but proxy events do not fire

Foliage starts as a virtual focus target. The proxy actor is spawned only when the interaction begins or needs an actor-backed runtime state. Debug the handoff before changing Blueprint logic.

• Confirm that the foliage mesh has a matching entry in FoliageDatabase or FoliageDataTable.
• Confirm that the entry has a valid ProxyActorClass with an interactable component.
• Verify that the slot exists on the proxy after initialization.
• Use the proxy events such as OnProxyReady, OnFoliageHoldStarted, OnFoliageHit, and OnFoliageCompleted.
• If you want custom falling/chopping/dissolve timing, call ResolveProxyLifecycle from Blueprint when the visual sequence is ready.
• Enable ie.Debug.Foliage.EventTrace 1, ie.Debug.FoliageProxy 1, and ie.Debug.Transaction 1.

Foliage changes on the server but not on clients

• Make sure source instance visibility and proxy visibility are changed through the plugin's foliage/proxy APIs, not by local-only Blueprint changes.
• Confirm that the interaction is completed on the server and that clients receive confirmed events.
• Check whether the proxy is replicated and relevant to the clients that should see it.
• Use HideSourceInstance, ShowSourceInstance, SetSourceInstanceHidden, HideProxy, ShowProxy, or SetProxyHidden instead of ad-hoc visibility changes.
• Enable ie.Debug.Net 1 and ie.Debug.FoliageProxy 1.

Save/load works for actors, but not for foliage

• Use Store All Foliage Proxy Snapshots and Restore All Foliage Proxy Snapshots for the recommended world-level foliage persistence flow.
• Use the older Store Foliage Snapshots and Restore Foliage Snapshots nodes only for legacy or per-interactor cases.
• Run save and restore logic on the server in multiplayer.
• Confirm that the snapshot contains stable source instance data, source hidden state, proxy hidden state, and interactable state.
• If using World Partition or streaming, restore again after the relevant level/foliage source is loaded.
• Enable ie.Debug.SaveLoad 1 and ie.Debug.Foliage.EventTrace 1.

Runtime slot changes do not replicate correctly

• Do not directly edit the static Slots array after BeginPlay.
• Use the component API for runtime changes such as SetSlotEnabled, SetSlotBlocked, SetSlotHealth, ApplyDamageToSlot, ResetSlot, and cooldown functions.
• Remember that SlotRuntimeStates is the replicated runtime state path.
• Perform authoritative runtime state changes on the server.
• Use OnSlotsStateChanged or confirmed interaction events to refresh Blueprint UI and gameplay state.

UI attaches to the wrong position

• Confirm whether the actor uses an Interaction Widget Anchor Component.
• Review FocusWidgetPlacementMode, WidgetRelativeOffset, FixedScreenPosition, and FixedScreenWidgetOffset.
• For foliage, check the entry's widget placement settings because the widget may be shown before the proxy exists.
• For projected widgets, confirm that the target is inside the camera frustum and not behind the camera.

Diagnostic order