diff --git a/x-pack/test/functional_with_es_ssl/apps/discover_ml_uptime/discover/search_source_alert.ts b/x-pack/test/functional_with_es_ssl/apps/discover_ml_uptime/discover/search_source_alert.ts
index ece232dae39a86..04c3bb1e644583 100644
--- a/x-pack/test/functional_with_es_ssl/apps/discover_ml_uptime/discover/search_source_alert.ts
+++ b/x-pack/test/functional_with_es_ssl/apps/discover_ml_uptime/discover/search_source_alert.ts
@@ -13,7 +13,14 @@ export default function ({ getService, getPageObjects }: FtrProviderContext) {
   const log = getService('log');
   const es = getService('es');
   const monacoEditor = getService('monacoEditor');
-  const PageObjects = getPageObjects(['settings', 'common', 'header', 'discover', 'timePicker']);
+  const PageObjects = getPageObjects([
+    'settings',
+    'common',
+    'header',
+    'discover',
+    'timePicker',
+    'unifiedFieldList',
+  ]);
   const deployment = getService('deployment');
   const dataGrid = getService('dataGrid');
   const browser = getService('browser');
@@ -325,8 +332,7 @@ export default function ({ getService, getPageObjects }: FtrProviderContext) {
     expect(await titleElem.getAttribute('value')).to.equal(dataView);
   };
 
-  // FLAKY: https://github.com/elastic/kibana/issues/190090
-  describe.skip('Search source Alert', () => {
+  describe('Search source Alert', () => {
     before(async () => {
       await security.testUser.setRoles(['discover_alert']);
 
@@ -527,7 +533,13 @@ export default function ({ getService, getPageObjects }: FtrProviderContext) {
       });
 
       await PageObjects.timePicker.setCommonlyUsedTime('Last_15 minutes');
+      await PageObjects.header.waitUntilLoadingHasFinished();
       await PageObjects.discover.addRuntimeField('runtime-message-field', `emit('mock-message')`);
+      await retry.try(async () => {
+        expect(await PageObjects.unifiedFieldList.getAllFieldNames()).to.contain(
+          'runtime-message-field'
+        );
+      });
 
       // create an alert
       await openDiscoverAlertFlyout();
diff --git a/x-pack/test_serverless/functional/test_suites/common/discover_ml_uptime/discover/search_source_alert.ts b/x-pack/test_serverless/functional/test_suites/common/discover_ml_uptime/discover/search_source_alert.ts
index 4708d1f453c315..f851893adb19dc 100644
--- a/x-pack/test_serverless/functional/test_suites/common/discover_ml_uptime/discover/search_source_alert.ts
+++ b/x-pack/test_serverless/functional/test_suites/common/discover_ml_uptime/discover/search_source_alert.ts
@@ -21,6 +21,7 @@ export default function ({ getService, getPageObjects }: FtrProviderContext) {
     'discover',
     'timePicker',
     'dashboard',
+    'unifiedFieldList',
   ]);
   const deployment = getService('deployment');
   const dataGrid = getService('dataGrid');
@@ -364,7 +365,7 @@ export default function ({ getService, getPageObjects }: FtrProviderContext) {
     expect(await titleElem.getAttribute('value')).to.equal(dataView);
   };
 
-  describe('Search source Alert', function () {
+  describe('Search source Alert', () => {
     before(async () => {
       await security.testUser.setRoles(['discover_alert']);
       await PageObjects.svlCommonPage.loginAsAdmin();
@@ -562,7 +563,13 @@ export default function ({ getService, getPageObjects }: FtrProviderContext) {
       });
 
       await PageObjects.timePicker.setCommonlyUsedTime('Last_15 minutes');
+      await PageObjects.header.waitUntilLoadingHasFinished();
       await PageObjects.discover.addRuntimeField('runtime-message-field', `emit('mock-message')`);
+      await retry.try(async () => {
+        expect(await PageObjects.unifiedFieldList.getAllFieldNames()).to.contain(
+          'runtime-message-field'
+        );
+      });
 
       // create an alert
       await openDiscoverAlertFlyout();