debounceTime does not emit when queueScheduler is used

Describe the bug

If synchronous scheduler is used and there are no other tasks debounceTime does not emit value to subscriber.

Expected behavior

debounceTime should work properly with queueScheduler as it was in v6

expected output

emit!

actual output

No emit at all

Reproduction code

import { BehaviorSubject, queueScheduler } from 'rxjs';
import { debounceTime } from 'rxjs/operators';

const data$ = new BehaviorSubject('emit!');

data$.pipe(debounceTime(0, queueScheduler)).subscribe(console.log);

Reproduction URL

https://stackblitz.com/edit/q7u9jg-hykb4x

Version

7.5.1

Environment

No response

Additional context

No response

Start with the debounceTime operator and its queueScheduler path, then run the reproduction code from the issue with RxJS 7.5.1. Confirm that debounceTime(0, queueScheduler) emits emit! from the BehaviorSubject, matching the expected behavior and not the current lack of output.