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.
const currentPrimaryChildFragment: Fiber = (current.child: any);
      const currentFallbackChildFragment: Fiber = (currentPrimaryChildFragment.sibling: any);
      if (nextDidTimeout) {
         
         
        const nextFallbackChildren = nextProps.fallback;
        const primaryChildFragment = createWorkInProgress(
          currentPrimaryChildFragment,
          currentPrimaryChildFragment.pendingProps,
        );
        primaryChildFragment.return = workInProgress;
        if ((workInProgress.mode & BlockingMode) === NoMode) {
           
           
          const progressedState: SuspenseState = workInProgress.memoizedState;
          const progressedPrimaryChild: Fiber | null =
            progressedState !== null
              ? (workInProgress.child: any).child
              : (workInProgress.child: any);
          if (progressedPrimaryChild !== currentPrimaryChildFragment.child) {
            primaryChildFragment.child = progressedPrimaryChild;
            let progressedChild = progressedPrimaryChild;
            while (progressedChild !== null) {
              progressedChild.return = primaryChildFragment;
              progressedChild = progressedChild.sibling;
            }
          }
        }