diff --git a/vaadin-combo-box-flow-parent/vaadin-combo-box-flow-integration-tests/src/test/java/com/vaadin/flow/component/combobox/test/LazyComboBoxFilterIT.java b/vaadin-combo-box-flow-parent/vaadin-combo-box-flow-integration-tests/src/test/java/com/vaadin/flow/component/combobox/test/LazyComboBoxFilterIT.java
index 6c3801ff0e0..27674edd475 100644
--- a/vaadin-combo-box-flow-parent/vaadin-combo-box-flow-integration-tests/src/test/java/com/vaadin/flow/component/combobox/test/LazyComboBoxFilterIT.java
+++ b/vaadin-combo-box-flow-parent/vaadin-combo-box-flow-integration-tests/src/test/java/com/vaadin/flow/component/combobox/test/LazyComboBoxFilterIT.java
@@ -15,10 +15,14 @@
  */
 package com.vaadin.flow.component.combobox.test;
 
-import org.junit.Assert;
+import java.time.Duration;
+import java.time.temporal.ChronoUnit;
+
 import org.junit.Test;
 import org.openqa.selenium.By;
 import org.openqa.selenium.WebElement;
+import org.openqa.selenium.support.ui.ExpectedConditions;
+import org.openqa.selenium.support.ui.WebDriverWait;
 
 import com.vaadin.flow.component.combobox.testbench.ComboBoxElement;
 import com.vaadin.flow.testutil.TestPath;
@@ -35,7 +39,10 @@ public void lazyComboBoxFilterFirstQuery() {
         comboBox.openPopup();
 
         WebElement query = findElement(By.id("query"));
-        Assert.assertTrue(query.getText().contains("Filter: 1"));
-        Assert.assertTrue(query.getText().contains("Count: 10"));
+
+        WebDriverWait wait = new WebDriverWait(driver,
+                Duration.of(2, ChronoUnit.SECONDS));
+        wait.until(ExpectedConditions.textToBePresentInElement(query,
+                "Filter: 1 Count: 10"));
     }
 }
diff --git a/vaadin-combo-box-flow-parent/vaadin-combo-box-flow/src/main/java/com/vaadin/flow/component/combobox/ComboBoxBase.java b/vaadin-combo-box-flow-parent/vaadin-combo-box-flow/src/main/java/com/vaadin/flow/component/combobox/ComboBoxBase.java
index 2ace4e489a8..e5c35a7f79a 100644
--- a/vaadin-combo-box-flow-parent/vaadin-combo-box-flow/src/main/java/com/vaadin/flow/component/combobox/ComboBoxBase.java
+++ b/vaadin-combo-box-flow-parent/vaadin-combo-box-flow/src/main/java/com/vaadin/flow/component/combobox/ComboBoxBase.java
@@ -99,6 +99,8 @@ public abstract class ComboBoxBase<TComponent extends ComboBoxBase<TComponent, T
         HasValidationProperties, HasValidator<TValue>, HasPlaceholder {
     private static final int DEFAULT_FILTER_TIMEOUT = 500;
 
+    private String lastKnownFilter;
+
     /**
      * Registration for custom value listeners that disallows entering custom
      * values as soon as there are no more listeners for the custom value event
@@ -346,9 +348,8 @@ public void setAllowCustomValue(boolean allowCustomValue) {
      *
      * @return the filter string
      */
-    @Synchronize(property = "filter", value = "filter-changed")
     protected String getFilter() {
-        return getElement().getProperty("filter");
+        return lastKnownFilter;
     }
 
     /**
@@ -359,7 +360,11 @@ protected String getFilter() {
      * @param filter
      *            the String value to set
      */
+    @Deprecated
     protected void setFilter(String filter) {
+        lastKnownFilter = filter;
+        // MT 20250-02-21 I assume client side never uses this, probably the
+        // whole method is obsolete
         getElement().setProperty("filter", filter == null ? "" : filter);
     }
 
@@ -1367,6 +1372,7 @@ private void confirmUpdate(int id) {
      */
     @ClientCallable
     private void setViewportRange(int start, int length, String filter) {
+        this.lastKnownFilter = filter;
         dataController.setViewportRange(start, length, filter);
     }