diff --git a/src/openforms/js/components/admin/form_design/variables/prefill/ObjectsAPIFields.js b/src/openforms/js/components/admin/form_design/variables/prefill/ObjectsAPIFields.js
index fe7df3214a..2627b132eb 100644
--- a/src/openforms/js/components/admin/form_design/variables/prefill/ObjectsAPIFields.js
+++ b/src/openforms/js/components/admin/form_design/variables/prefill/ObjectsAPIFields.js
@@ -198,7 +198,6 @@ const ObjectsAPIFields = ({errors}) => {
           }}
           name="options.objectsApiGroup"
           onApiGroupChange={onApiGroupChange}
-          selectProps={{maxMenuHeight: '16em', menuPlacement: 'bottom'}}
         />
 
         <ErrorBoundary
@@ -215,7 +214,6 @@ const ObjectsAPIFields = ({errors}) => {
             name="options.objecttypeUuid"
             apiGroupFieldName="options.objectsApiGroup"
             versionFieldName="options.objecttypeVersion"
-            selectProps={{maxMenuHeight: '16em', menuPlacement: 'bottom'}}
             onChangeCheck={async () => {
               if (variablesMapping.length === 0) return true;
               const confirmSwitch = await openObjectTypeConfirmationModal();
@@ -240,7 +238,6 @@ const ObjectsAPIFields = ({errors}) => {
             name="options.objecttypeVersion"
             apiGroupFieldName="options.objectsApiGroup"
             objectTypeFieldName="options.objecttypeUuid"
-            selectProps={{maxMenuHeight: '16em', menuPlacement: 'bottom'}}
           />
         </ErrorBoundary>
 
diff --git a/src/openforms/js/components/admin/forms/ReactSelect.js b/src/openforms/js/components/admin/forms/ReactSelect.js
index 263d9c838f..58e3f446e2 100644
--- a/src/openforms/js/components/admin/forms/ReactSelect.js
+++ b/src/openforms/js/components/admin/forms/ReactSelect.js
@@ -82,6 +82,7 @@ const SelectWithoutFormik = ({name, options, value, className, onChange, ...prop
     classNamePrefix="admin-react-select"
     styles={styles}
     menuPlacement="auto"
+    menuPortalTarget={document.body}
     options={options}
     value={getValue(options, value)}
     onChange={selectedOption => {
@@ -107,6 +108,7 @@ const SelectWithFormik = ({name, options, className, ...props}) => {
       classNamePrefix="admin-react-select"
       styles={styles}
       menuPlacement="auto"
+      menuPortalTarget={document.body}
       options={options}
       {...fieldProps}
       value={getValue(options, value)}
diff --git a/src/openforms/js/components/admin/forms/objects_api/ObjectTypeSelect.js b/src/openforms/js/components/admin/forms/objects_api/ObjectTypeSelect.js
index 630c1628bf..5e80d60cd3 100644
--- a/src/openforms/js/components/admin/forms/objects_api/ObjectTypeSelect.js
+++ b/src/openforms/js/components/admin/forms/objects_api/ObjectTypeSelect.js
@@ -25,7 +25,6 @@ const ObjectTypeSelect = ({
   apiGroupFieldName = 'objectsApiGroup',
   onChangeCheck,
   versionFieldName = 'objecttypeVersion',
-  selectProps = {},
 }) => {
   const [fieldProps, , fieldHelpers] = useField(name);
   const {
@@ -95,7 +94,6 @@ const ObjectTypeSelect = ({
             const okToProceed = onChangeCheck === undefined || onChangeCheck();
             if (okToProceed) setValue(selectedOption.value);
           }}
-          {...selectProps}
         />
       </Field>
     </FormRow>
@@ -122,11 +120,6 @@ ObjectTypeSelect.propTypes = {
    * changes, the version will be reset/unset.
    */
   versionFieldName: PropTypes.string,
-
-  /**
-   * Additional properties to be forwarded to the React select component
-   */
-  selectProps: PropTypes.object,
 };
 
 export default ObjectTypeSelect;
diff --git a/src/openforms/js/components/admin/forms/objects_api/ObjectTypeVersionSelect.js b/src/openforms/js/components/admin/forms/objects_api/ObjectTypeVersionSelect.js
index 594e22dfa0..63a4b7028a 100644
--- a/src/openforms/js/components/admin/forms/objects_api/ObjectTypeVersionSelect.js
+++ b/src/openforms/js/components/admin/forms/objects_api/ObjectTypeVersionSelect.js
@@ -29,7 +29,6 @@ const ObjectTypeVersionSelect = ({
   name = 'objecttypeVersion',
   apiGroupFieldName = 'objectsApiGroup',
   objectTypeFieldName = 'objecttype',
-  selectProps = {},
 }) => {
   const {getFieldProps} = useFormikContext();
 
@@ -72,7 +71,6 @@ const ObjectTypeVersionSelect = ({
           options={options}
           isLoading={loading}
           isDisabled={!objecttype}
-          {...selectProps}
         />
       </Field>
     </FormRow>
@@ -94,10 +92,6 @@ ObjectTypeVersionSelect.propTypes = {
    * call to get the available object type versions.
    */
   objectTypeFieldName: PropTypes.string,
-  /**
-   * Additional properties to be forwarded to the React select component
-   */
-  selectProps: PropTypes.object,
 };
 
 export default ObjectTypeVersionSelect;
diff --git a/src/openforms/js/components/admin/forms/objects_api/ObjectsAPIGroup.js b/src/openforms/js/components/admin/forms/objects_api/ObjectsAPIGroup.js
index 3ec3556186..3354714044 100644
--- a/src/openforms/js/components/admin/forms/objects_api/ObjectsAPIGroup.js
+++ b/src/openforms/js/components/admin/forms/objects_api/ObjectsAPIGroup.js
@@ -14,7 +14,6 @@ const ObjectsAPIGroup = ({
   onApiGroupChange,
   isClearable = false,
   required = true,
-  selectProps = {},
 }) => {
   const [{onChange: onChangeFormik, ...fieldProps}, , {setValue}] = useField(name);
   const {setValues} = useFormikContext();
@@ -69,7 +68,6 @@ const ObjectsAPIGroup = ({
             }
           }}
           isClearable={isClearable}
-          {...selectProps}
         />
       </Field>
     </FormRow>
@@ -121,11 +119,6 @@ ObjectsAPIGroup.propTypes = {
    * Indicate if the field is required or optional.
    */
   required: PropTypes.bool,
-
-  /**
-   * Additional properties to be forwarded to the React select component
-   */
-  selectProps: PropTypes.object,
 };
 
 export default ObjectsAPIGroup;
diff --git a/src/openforms/scss/components/admin/_ReactModal.scss b/src/openforms/scss/components/admin/_ReactModal.scss
index 51f867573b..0f8e2eb91a 100644
--- a/src/openforms/scss/components/admin/_ReactModal.scss
+++ b/src/openforms/scss/components/admin/_ReactModal.scss
@@ -7,7 +7,9 @@
     align-items: center;
 
     position: fixed;
-    z-index: 1000;
+    // the base admin layout gets a z-index up until 2, so this ensures it's layered on top of the admin
+    // while leaving enough space for other UI elements on top of that (like react-select)
+    z-index: 3;
     top: 0;
     right: 0;
     bottom: 0;
diff --git a/src/openforms/scss/vendor/_react-select.scss b/src/openforms/scss/vendor/_react-select.scss
index 7742660e24..42649d6b99 100644
--- a/src/openforms/scss/vendor/_react-select.scss
+++ b/src/openforms/scss/vendor/_react-select.scss
@@ -26,4 +26,8 @@
     var(--of-admin-select-max-inline-size)
   );
   max-inline-size: var(--of-admin-select-max-inline-size);
+
+  &__menu-portal {
+    z-index: 4 !important; // one higher than the react-modal z-index
+  }
 }