Apple Maps Won't Navigate (Sporadic Problem)
This happens whenever the "From" location is a fixed address, rather than "Current location". Even if that address is your current location when you start, Maps will be in a different mode, as you have discovered.

To switch from the static navigation mode to turn-by-turn mode:


Tap End.
Choose those directions again.
Don't tap Go yet. Tap the blue text after "From".
Replace the text there with "Current location" and tap Route.
Now tap Go.


Routes with a fixed start address would probably be from Apple Maps on your Mac, which doesn't offer turn-by-turn directions. If you want to remove these from your history on your iPhone, swipe left on those items in the list.