I'm not an expert on blendshapes but I believe you have to delete your unused node in hypergraph, by select the model node and click 'input and output connections' in hypergraph windows. Then try deleting your history.
I'm not an expert on blendshapes but I believe you have to delete your unused node in hypergraph, by select the model node and click 'input and output connections' in hypergraph windows. Then try deleting your history.