Cannot sync Google Drive between MacBook and iPhone app
Just clicking on Search drive in the app was sufficient to jiggle something loose and sync cloud -&gt; iphone.

I noticed one glitch. The iPhone Drive app was failing to display bar.txt which IS on cloud (I added it yesterday), but instead was still displaying a foo.pdf file that longer exists on the cloud (which was showing up even before I asked the question), and bizarrely clicking on foo.pdf actually shows the contents of bar.txt.

Reinstalling the Drive App resolves this.

EDIT: I can recreate the problem as follows:
 - On my MacBook I copy X.txt to ~/google-drive
 - Observe that the cloud icon in the tray does sync animation
 - Observe that X.txt does not appear on Drive app
 - Drive App -> Search drive for X.txt
 - Now it is visible