RNA property for the third input contains a typo. Changing Input Type C changes Input Type B.
See: source/blender/makesrna/intern/rna_nodetree.c
References Input B
prop = RNA_def_property(srna, "input_type_c", PROP_ENUM, PROP_NONE); RNA_def_property_enum_bitflag_sdna(prop, NULL, "input_type_b"); RNA_def_property_enum_items(prop, rna_node_geometry_attribute_input_type_items_vector); RNA_def_property_ui_text(prop, "Input Type B", ""); RNA_def_property_update(prop, NC_NODE | NA_EDITED, "rna_Node_socket_update");
Should be:
prop = RNA_def_property(srna, "input_type_c", PROP_ENUM, PROP_NONE); RNA_def_property_enum_bitflag_sdna(prop, NULL, "input_type_c"); RNA_def_property_enum_items(prop, rna_node_geometry_attribute_input_type_items_vector); RNA_def_property_ui_text(prop, "Input Type C", ""); RNA_def_property_update(prop, NC_NODE | NA_EDITED, "rna_Node_socket_update");