https://codesandbox.io/s/upbeat-frost-3tt25

1. Press Suspend, see "Loading..."
2. Wait five seconds, you'll see "Happy birthday" at some point 
3. You won't see it again no matter how long you wait

Expected: you'll see it every five seconds.
let hiddenChild = primaryChildFragment.child;
          while (hiddenChild !== null) {
            treeBaseDuration += hiddenChild.treeBaseDuration;
            hiddenChild = hiddenChild.sibling;
          }
          primaryChildFragment.treeBaseDuration = treeBaseDuration;
        }
         
        const fallbackChildFragment = createFiberFromFragment(
          nextFallbackChildren,
          mode,
          renderExpirationTime,
          null,
        );
        fallbackChildFragment.return = workInProgress;
        primaryChildFragment.sibling = fallbackChildFragment;
        fallbackChildFragment.effectTag |= Placement;
        primaryChildFragment.childExpirationTime = NoWork;
         
         
        workInProgress.memoizedState = SUSPENDED_MARKER;
        workInProgress.child = primaryChildFragment;
        return fallbackChildFragment;
      } else {
         
         
        workInProgress.memoizedState = null;
        const nextPrimaryChildren = nextProps.children;
        return (workInProgress.child = reconcileChildFibers(
          workInProgress,