diff --git a/src/vs/editor/contrib/suggest/suggestModel.ts b/src/vs/editor/contrib/suggest/suggestModel.ts
index d3daa598ebb..4a37a446830 100644
--- a/src/vs/editor/contrib/suggest/suggestModel.ts
+++ b/src/vs/editor/contrib/suggest/suggestModel.ts
@@ -229,7 +229,7 @@ export class SuggestModel implements IDisposable {
 			if (supports) {
 				// keep existing items that where not computed by the
 				// supports/providers that want to trigger now
-				const items: CompletionItem[] | undefined = this._completionModel ? this._completionModel.adopt(supports) : undefined;
+				const items = this._completionModel?.adopt(supports);
 				this.trigger({ auto: true, shy: false, triggerCharacter: lastChar }, Boolean(this._completionModel), supports, items);
 			}
 		};
diff --git a/src/vs/editor/contrib/suggest/test/suggestModel.test.ts b/src/vs/editor/contrib/suggest/test/suggestModel.test.ts
index 8c75309d28d..a17c34495bc 100644
--- a/src/vs/editor/contrib/suggest/test/suggestModel.test.ts
+++ b/src/vs/editor/contrib/suggest/test/suggestModel.test.ts
@@ -791,4 +791,61 @@ suite('SuggestModel - TriggerAndCancelOracle', function () {
 
 		});
 	});
+
+
+	test('Trigger (full) completions when (incomplete) completions are already active #99504', function () {
+		this.skip();
+
+		disposables.push(CompletionProviderRegistry.register({ scheme: 'test' }, {
+			provideCompletionItems(doc, pos) {
+				return {
+					incomplete: true,
+					suggestions: [{
+						kind: CompletionItemKind.Class,
+						label: 'Z aaa',
+						insertText: 'Z aaa',
+						range: new Range(1, 1, pos.lineNumber, pos.column)
+					}],
+				};
+			}
+		}));
+		disposables.push(CompletionProviderRegistry.register({ scheme: 'test' }, {
+			provideCompletionItems(doc, pos) {
+				return {
+					incomplete: false,
+					suggestions: [{
+						kind: CompletionItemKind.Folder,
+						label: 'aaa',
+						insertText: 'aaa',
+						range: getDefaultSuggestRange(doc, pos)
+					}],
+				};
+			},
+		}));
+
+		return withOracle(async (model, editor) => {
+
+			await assertEvent(model.onDidSuggest, () => {
+				editor.setValue('');
+				editor.setSelection(new Selection(1, 1, 1, 1));
+				editor.trigger('keyboard', Handler.Type, { text: 'Z' });
+
+			}, event => {
+				assert.equal(event.auto, true);
+				assert.equal(event.completionModel.items.length, 1);
+				assert.equal(event.completionModel.items[0].textLabel, 'Z aaa');
+			});
+
+			await assertEvent(model.onDidSuggest, () => {
+				// started another word: Z a|
+				// item should be: Z aaa, aaa
+				editor.trigger('keyboard', Handler.Type, { text: ' a' });
+			}, event => {
+				assert.equal(event.auto, true);
+				assert.equal(event.completionModel.items.length, 2);
+				assert.equal(event.completionModel.items[0].textLabel, 'Z aaa');
+				assert.equal(event.completionModel.items[1].textLabel, 'aaa');
+			});
+		});
+	});
 });