Background:

E-tool has a placement mode that can be used for placing items like sandbags. The target entity one tries to place on top gets validated in SCR_ItemPlacementComponent::ValidateEntity. The validation is cached, i.e. ValidateEntity only gets executed when the target entity changes (see SCR_ItemPlacementComponent::ValidatePlacement). Items can have specific rules to control what kind of target entities are allowed, e.g. SCR_PlaceableItemComponentClass::m_aIgnoredComponents.

Issue:

When switching between placeable items while in E-tool's placement mode (default PC keybind C; executes SCR_CampaignBuildingGadgetToolComponent::CycleItems), ValidateEntity does not get executed because of the caching, and hence the rules of the new item do not get applied until the target entity changes.

Related:

https://github.com/acemod/ACE-Anvil/pull/498