diff --git a/src/components/autocomplete/AutoComplete.vue b/src/components/autocomplete/AutoComplete.vue
index 973f2a3ab..23774aab0 100755
--- a/src/components/autocomplete/AutoComplete.vue
+++ b/src/components/autocomplete/AutoComplete.vue
@@ -783,6 +783,16 @@ export default {
             this.$emit('update:modelValue', value);
             this.$emit('change', { originalEvent: event, value });
         },
+        flatOptions(options = []) {
+            return options.reduce((result, option, index) => {
+                result.push({ optionGroup: option, group: true, index });
+
+                const optionGroupChildren = this.getOptionGroupChildren(option);
+                optionGroupChildren && optionGroupChildren.forEach(o => result.push(o));
+
+                return result;
+            }, []);
+        },
         overlayRef(el) {
             this.overlay = el;
         },
@@ -824,20 +834,7 @@ export default {
             return ['p-autocomplete-loader pi-spin', this.loadingIcon];
         },
         visibleOptions() {
-            let options = this.suggestions || [];
-
-            if (this.optionGroupLabel) {
-                options = options.reduce((result, option, index) => {
-                    result.push({ optionGroup: option, group: true, index });
-
-                    let optionGroupChildren = this.getOptionGroupChildren(option);
-                    optionGroupChildren && optionGroupChildren.forEach(o => result.push(o));
-
-                    return result;
-                }, []);
-            }
-
-            return options;
+            return this.optionGroupLabel ? this.flatOptions(this.suggestions) : (this.suggestions || []);
         },
         inputValue() {
             if (this.modelValue) {
diff --git a/src/components/dropdown/Dropdown.vue b/src/components/dropdown/Dropdown.vue
index 969d1b26c..d7065c695 100755
--- a/src/components/dropdown/Dropdown.vue
+++ b/src/components/dropdown/Dropdown.vue
@@ -771,6 +771,16 @@ export default {
             this.$emit('update:modelValue', value);
             this.$emit('change', { originalEvent: event, value });
         },
+        flatOptions(options = []) {
+            return options.reduce((result, option, index) => {
+                result.push({ optionGroup: option, group: true, index });
+
+                const optionGroupChildren = this.getOptionGroupChildren(option);
+                optionGroupChildren && optionGroupChildren.forEach(o => result.push(o));
+
+                return result;
+            }, []);
+        },
         overlayRef(el) {
             this.overlay = el;
         },
@@ -809,18 +819,7 @@ export default {
             return ['p-dropdown-trigger-icon', (this.loading ? this.loadingIcon : 'pi pi-chevron-down')];
         },
         visibleOptions() {
-            let options = this.options || [];
-
-            if (this.optionGroupLabel) {
-                options = options.reduce((result, option, index) => {
-                    result.push({ optionGroup: option, group: true, index });
-
-                    let optionGroupChildren = this.getOptionGroupChildren(option);
-                    optionGroupChildren && optionGroupChildren.forEach(o => result.push(o));
-
-                    return result;
-                }, []);
-            }
+            const options = this.optionGroupLabel ? this.flatOptions(this.options) : (this.options || []);
 
             return this.filterValue ? FilterService.filter(options, this.searchFields, this.filterValue, this.filterMatchMode, this.filterLocale) : options;
         },
diff --git a/src/components/listbox/Listbox.vue b/src/components/listbox/Listbox.vue
index 17bb38479..f35066c4e 100755
--- a/src/components/listbox/Listbox.vue
+++ b/src/components/listbox/Listbox.vue
@@ -621,6 +621,16 @@ export default {
             this.$emit('update:modelValue', value);
             this.$emit('change', { originalEvent: event, value });
         },
+        flatOptions(options = []) {
+            return options.reduce((result, option, index) => {
+                result.push({ optionGroup: option, group: true, index });
+
+                const optionGroupChildren = this.getOptionGroupChildren(option);
+                optionGroupChildren && optionGroupChildren.forEach(o => result.push(o));
+
+                return result;
+            }, []);
+        },
         listRef(el, contentRef) {
             this.list = el;
             contentRef && contentRef(el); // For VirtualScroller
@@ -637,18 +647,7 @@ export default {
             }];
         },
         visibleOptions() {
-            let options = this.options || [];
-
-            if (this.optionGroupLabel) {
-                options = options.reduce((result, option, index) => {
-                    result.push({ optionGroup: option, group: true, index });
-
-                    let optionGroupChildren = this.getOptionGroupChildren(option);
-                    optionGroupChildren && optionGroupChildren.forEach(o => result.push(o));
-
-                    return result;
-                }, []);
-            }
+            const options = this.optionGroupLabel ? this.flatOptions(this.options) : (this.options || []);
 
             return this.filterValue ? FilterService.filter(options, this.searchFields, this.filterValue, this.filterMatchMode, this.filterLocale) : options;
         },
diff --git a/src/components/multiselect/MultiSelect.vue b/src/components/multiselect/MultiSelect.vue
index 946ca6a7c..772d48adf 100755
--- a/src/components/multiselect/MultiSelect.vue
+++ b/src/components/multiselect/MultiSelect.vue
@@ -901,6 +901,16 @@ export default {
             this.$emit('update:modelValue', value);
             this.$emit('change', { originalEvent: event, value });
         },
+        flatOptions(options = []) {
+            return options.reduce((result, option, index) => {
+                result.push({ optionGroup: option, group: true, index });
+
+                const optionGroupChildren = this.getOptionGroupChildren(option);
+                optionGroupChildren && optionGroupChildren.forEach(o => result.push(o));
+
+                return result;
+            }, []);
+        },
         overlayRef(el) {
             this.overlay = el;
         },
@@ -939,18 +949,7 @@ export default {
             }];
         },
         visibleOptions() {
-            let options = this.options || [];
-
-            if (this.optionGroupLabel) {
-                options = options.reduce((result, option, index) => {
-                    result.push({ optionGroup: option, group: true, index });
-
-                    let optionGroupChildren = this.getOptionGroupChildren(option);
-                    optionGroupChildren && optionGroupChildren.forEach(o => result.push(o));
-
-                    return result;
-                }, []);
-            }
+            const options = this.optionGroupLabel ? this.flatOptions(this.options) : (this.options || []);
 
             return this.filterValue ? FilterService.filter(options, this.searchFields, this.filterValue, this.filterMatchMode, this.filterLocale) : options;
         },