Exclude isCycleStart in export

lib/import-export/get-csv-column-names.js

@@ -7,6 +7,9 @@ export default function getColumnNamesForCsv() {
     const schema = getSchema()
     const model = schema[schemaName]
     return Object.keys(model).reduce((acc, key) => {
+      // we don't want to include isCycleStart, because that is
+      // a derived value
+      if (key === 'isCycleStart') return acc
       const prefixedKey = prefix ? [prefix, key].join('.') : key
       const childSchemaName = model[key].objectType
       if (!childSchemaName) {