updated computed label logic for multiple casers

1) when computing the label,  use  all options verses just visible options
this new logic will find the selected option whether or not the user is currently filtering  because the filtered (i.e. visible) options, are a subset of all the options
2) When finding selected option,  consider all options even those that have been disabled

src/app/components/dropdown/dropdown.ts

@@ -903,7 +903,7 @@ export class Dropdown implements OnInit, AfterViewInit, AfterContentInit, AfterV
     }
 
     visibleOptions = computed(() => {
-        const options = this.group ? this.flatOptions(this.options) : this.options || [];
+        const options = this.getAllVisibleAndNonVisibleOptions();
 
         if (this._filterValue()) {
             const _filterBy = this.filterBy || this.optionLabel;
@@ -938,9 +938,13 @@ export class Dropdown implements OnInit, AfterViewInit, AfterContentInit, AfterV
     });
 
     label = computed(() => {
-        const selectedOptionIndex = this.findSelectedOptionIndex();
+        // use  getAllVisibleAndNonVisibleOptions verses just visible options
+        // this will find the selected option whether or not the user is currently filtering  because the filtered (i.e. visible) options, are a subset of all the options
+        const options = this.getAllVisibleAndNonVisibleOptions();
+        // use isOptionEqualsModelValue for the use case where the dropdown is initalized with a disabled option
+        const selectedOptionIndex = options.findIndex((option) => this.isOptionEqualsModelValue(option));
 
-        return selectedOptionIndex !== -1 ? this.getOptionLabel(this.visibleOptions()[selectedOptionIndex]) : this.placeholder() || 'p-emptylabel';
+        return selectedOptionIndex !== -1 ? this.getOptionLabel(options[selectedOptionIndex]) : this.placeholder() || 'p-emptylabel';
     });
 
     filled = computed(() => {
@@ -971,6 +975,10 @@ export class Dropdown implements OnInit, AfterViewInit, AfterContentInit, AfterV
         });
     }
 
+    private getAllVisibleAndNonVisibleOptions() {
+        return this.group ? this.flatOptions(this.options) : this.options || [];
+    }
+
     ngOnInit() {
         this.id = this.id || UniqueComponentId();
         this.autoUpdateModel();
@@ -1126,7 +1134,11 @@ export class Dropdown implements OnInit, AfterViewInit, AfterContentInit, AfterV
     }
 
     isSelected(option) {
-        return this.isValidOption(option) && ObjectUtils.equals(this.modelValue(), this.getOptionValue(option), this.equalityKey());
+        return this.isValidOption(option) && this.isOptionEqualsModelValue(option);
+    }
+
+    private isOptionEqualsModelValue(option: any) {
+        return ObjectUtils.equals(this.modelValue(), this.getOptionValue(option), this.equalityKey());
     }
 
     ngAfterViewInit() {