diff --git a/src-ui/src/app/components/common/custom-fields-query-dropdown/custom-fields-query-dropdown.component.ts b/src-ui/src/app/components/common/custom-fields-query-dropdown/custom-fields-query-dropdown.component.ts
index bebab5d0f..f556ec339 100644
--- a/src-ui/src/app/components/common/custom-fields-query-dropdown/custom-fields-query-dropdown.component.ts
+++ b/src-ui/src/app/components/common/custom-fields-query-dropdown/custom-fields-query-dropdown.component.ts
@@ -26,6 +26,30 @@ export class CustomFieldQueriesModel {
     }
   }
 
+  public isValid(): boolean {
+    return (
+      this.queries.length > 0 &&
+      this.validateExpression(this.queries[0] as CustomFieldQueryExpression)
+    )
+  }
+
+  private validateAtom(atom: CustomFieldQueryAtom) {
+    let valid: boolean = !!(atom.field && atom.operator && atom.value)
+    return valid
+  }
+
+  private validateExpression(expression: CustomFieldQueryExpression) {
+    return (
+      expression.operator &&
+      expression.value.length > 0 &&
+      (expression.value as CustomFieldQueryElement[]).every((e) =>
+        e.type === CustomFieldQueryElementType.Atom
+          ? this.validateAtom(e as CustomFieldQueryAtom)
+          : this.validateExpression(e as CustomFieldQueryExpression)
+      )
+    )
+  }
+
   public addQuery(query: CustomFieldQueryAtom) {
     if (this.queries.length === 0) {
       this.addExpression()
@@ -133,7 +157,7 @@ export class CustomFieldsQueryDropdownComponent {
       this._selectionModel.changed.complete()
     }
     model.changed.subscribe((updatedModel) => {
-      this.selectionModelChange.next(updatedModel)
+      this.onModelChange()
     })
     this._selectionModel = model
   }
@@ -142,6 +166,12 @@ export class CustomFieldsQueryDropdownComponent {
     return this._selectionModel
   }
 
+  private onModelChange() {
+    if (this.selectionModel.isValid()) {
+      this.selectionModelChange.next(this.selectionModel)
+    }
+  }
+
   @Output()
   selectionModelChange = new EventEmitter<CustomFieldQueriesModel>()
 
diff --git a/src-ui/src/app/components/document-list/filter-editor/filter-editor.component.ts b/src-ui/src/app/components/document-list/filter-editor/filter-editor.component.ts
index cf160bd19..3d95f473b 100644
--- a/src-ui/src/app/components/document-list/filter-editor/filter-editor.component.ts
+++ b/src-ui/src/app/components/document-list/filter-editor/filter-editor.component.ts
@@ -764,9 +764,9 @@ export class FilterEditorComponent
           })
         })
     }
-    let queries = this.customFieldQueriesModel.queries
-      .filter((query) => query.isValid)
-      .map((query) => query.serialize())
+    let queries = this.customFieldQueriesModel.queries.map((query) =>
+      query.serialize()
+    )
     if (queries.length > 0) {
       filterRules.push({
         rule_type: FILTER_CUSTOM_FIELDS_LOOKUP,
diff --git a/src-ui/src/app/data/custom-field-query.ts b/src-ui/src/app/data/custom-field-query.ts
index 4869710d0..784704356 100644
--- a/src-ui/src/app/data/custom-field-query.ts
+++ b/src-ui/src/app/data/custom-field-query.ts
@@ -64,7 +64,6 @@ export const CUSTOM_FIELD_QUERY_OPERATORS_BY_GROUP = {
     CustomFieldQueryOperator.GreaterThanOrEqual,
     CustomFieldQueryOperator.LessThan,
     CustomFieldQueryOperator.LessThanOrEqual,
-    // CustomFieldQueryOperator.Range,
   ],
   [CustomFieldQueryOperatorGroups.Containment]: [
     CustomFieldQueryOperator.Contains,
@@ -155,10 +154,6 @@ export class CustomFieldQueryElement {
     throw new Error('Implemented in subclass')
   }
 
-  public get isValid(): boolean {
-    throw new Error('Implemented in subclass')
-  }
-
   protected _operator: string = null
   public set operator(value: string) {
     this._operator = value
@@ -179,12 +174,12 @@ export class CustomFieldQueryElement {
 }
 
 export class CustomFieldQueryAtom extends CustomFieldQueryElement {
-  protected _field: string
-  set field(value: string) {
-    this._field = value
-    if (this.isValid) this.changed.next(this)
+  protected _field: number
+  set field(field: any) {
+    this._field = parseInt(field, 10)
+    this.changed.next(this)
   }
-  get field(): string {
+  get field(): number {
     return this._field
   }
 
@@ -217,7 +212,7 @@ export class CustomFieldQueryAtom extends CustomFieldQueryElement {
     return super.operator
   }
 
-  constructor(queryArray: [string, string, string] = [null, null, null]) {
+  constructor(queryArray: [number, string, string] = [null, null, null]) {
     super(CustomFieldQueryElementType.Atom)
     ;[this._field, this._operator, this._value] = queryArray
   }
@@ -233,10 +228,6 @@ export class CustomFieldQueryAtom extends CustomFieldQueryElement {
   public override serialize() {
     return [this._field, this._operator, this._value.toString()]
   }
-
-  public override get isValid(): boolean {
-    return !!(this._field && this._operator && this._value !== null)
-  }
 }
 
 export class CustomFieldQueryExpression extends CustomFieldQueryElement {
@@ -282,14 +273,6 @@ export class CustomFieldQueryExpression extends CustomFieldQueryElement {
     return [this._operator, value]
   }
 
-  public override get isValid(): boolean {
-    return (
-      this._operator &&
-      this._value.length > 0 &&
-      (this._value as any[]).every((v) => v.isValid)
-    )
-  }
-
   public addAtom(
     atom: CustomFieldQueryAtom = new CustomFieldQueryAtom([
       null,