diff --git a/x-pack/legacy/plugins/ml/public/application/jobs/new_job/common/job_creator/multi_metric_job_creator.ts b/x-pack/legacy/plugins/ml/public/application/jobs/new_job/common/job_creator/multi_metric_job_creator.ts
index 947c1bcf6c1a42..8a4411bf9025f7 100644
--- a/x-pack/legacy/plugins/ml/public/application/jobs/new_job/common/job_creator/multi_metric_job_creator.ts
+++ b/x-pack/legacy/plugins/ml/public/application/jobs/new_job/common/job_creator/multi_metric_job_creator.ts
@@ -92,12 +92,11 @@ export class MultiMetricJobCreator extends JobCreator {
       // not split field, use the default
       this.modelMemoryLimit = DEFAULT_MODEL_MEMORY_LIMIT;
     } else {
-      const fieldNames = this._detectors.map(d => d.field_name).filter(fn => fn !== undefined);
       const { modelMemoryLimit } = await ml.calculateModelMemoryLimit({
         indexPattern: this._indexPatternTitle,
         splitFieldName: this._splitField.name,
         query: this._datafeed_config.query,
-        fieldNames,
+        fieldNames: this.fields.map(f => f.id),
         influencerNames: this._influencers,
         timeFieldName: this._job_config.data_description.time_field,
         earliestMs: this._start,
diff --git a/x-pack/legacy/plugins/ml/public/application/jobs/new_job/pages/components/pick_fields_step/components/influencers/influencers.tsx b/x-pack/legacy/plugins/ml/public/application/jobs/new_job/pages/components/pick_fields_step/components/influencers/influencers.tsx
index c55bdeef4dde8f..5c5ba38b1c5a10 100644
--- a/x-pack/legacy/plugins/ml/public/application/jobs/new_job/pages/components/pick_fields_step/components/influencers/influencers.tsx
+++ b/x-pack/legacy/plugins/ml/public/application/jobs/new_job/pages/components/pick_fields_step/components/influencers/influencers.tsx
@@ -25,6 +25,9 @@ export const Influencers: FC = () => {
   useEffect(() => {
     jobCreator.removeAllInfluencers();
     influencers.forEach(i => jobCreator.addInfluencer(i));
+    if (jobCreator instanceof MultiMetricJobCreator) {
+      jobCreator.calculateModelMemoryLimit();
+    }
     jobCreatorUpdate();
   }, [influencers.join()]);