diff --git a/src/app/core/data/lookup-relation.service.ts b/src/app/core/data/lookup-relation.service.ts
index bf0e2469d1..153fcf1c54 100644
--- a/src/app/core/data/lookup-relation.service.ts
+++ b/src/app/core/data/lookup-relation.service.ts
@@ -1,6 +1,6 @@
 import { ExternalSourceService } from './external-source.service';
 import { SearchService } from '../shared/search/search.service';
-import { concat, map, multicast, startWith, take, takeWhile } from 'rxjs/operators';
+import { concat, distinctUntilChanged, map, multicast, startWith, take, takeWhile } from 'rxjs/operators';
 import { PaginatedSearchOptions } from '../../shared/search/paginated-search-options.model';
 import { ReplaySubject } from 'rxjs/internal/ReplaySubject';
 import { RemoteData } from './remote-data';
@@ -91,7 +91,8 @@ export class LookupRelationService {
       getAllSucceededRemoteData(),
       getRemoteDataPayload(),
       map((results: PaginatedList<ExternalSourceEntry>) => results.totalElements),
-      startWith(0)
+      startWith(0),
+      distinctUntilChanged()
     );
   }
 
diff --git a/src/app/shared/form/builder/ds-dynamic-form-ui/relation-lookup-modal/dynamic-lookup-relation-modal.component.ts b/src/app/shared/form/builder/ds-dynamic-form-ui/relation-lookup-modal/dynamic-lookup-relation-modal.component.ts
index c110c851fd..f2cba89005 100644
--- a/src/app/shared/form/builder/ds-dynamic-form-ui/relation-lookup-modal/dynamic-lookup-relation-modal.component.ts
+++ b/src/app/shared/form/builder/ds-dynamic-form-ui/relation-lookup-modal/dynamic-lookup-relation-modal.component.ts
@@ -233,7 +233,7 @@ export class DsDynamicLookupRelationModalComponent implements OnInit, OnDestroy
 
     this.totalExternal$ = externalSourcesAndOptions$.pipe(
       switchMap(([sources, options]) =>
-        observableZip(...sources.page.map((source: ExternalSource) => this.lookupRelationService.getTotalExternalResults(source, options))))
+        combineLatest(...sources.page.map((source: ExternalSource) => this.lookupRelationService.getTotalExternalResults(source, options))))
     );
   }