Swapping some ID lists between Mains must invalidate the name_map cache. Note that in theory, at least WM type could be ignored by name_map cache, since it is a singleton. However, don't think it's worth adding extra complication here, for really marginal benefits. The overhead of rebuilding the name cache here is extremly small. For some reason, this issue did not show so far in master, only appeared in some branch work on improving (in)direct status of linked IDs... Go figure.