Apple Watch maps app - how do I disappear the blank grid and get back to full-screen navigation instructions?

My new Apple Watch is afflicted by the apparently unsolvable blank-grid problem. Apparently the Watch can display a map but mine has never done it.

I like to use it for navigation though and it starts out nicely with full screen turn instructions, which are really useful, then somehow it switches to what I call fly-screen mode with the blank grid taking up most of the screen and the Nav directions scrunched into the top of the screen in tiny print.

I cannot figure out how to get the display back to no-grid mode with big Nav arrows. Any hints? I have tried randomly tapping stuff but it just makes me really annoyed and does nothing useful to the display.

And to maybe save some time, yes I have tried rebooting the phone and toggling Bluetooth and wifi and a host of other remedies for the blank grid problem without success. It is a flawed masterpiece and I live with it because the bits that do work are really good.

Now, if only I could get the grid to go away permanently, I would be almost happy.

Any clues?