Apple Watch workout app didn’t record gps data

Hi, I went for an outdoor run today and my Apple Watch Failed to record the GPS data. It shows my overall distance and mile splits still. But you can’t see where I went on the map - see attached screenshot. This is highly frustrating! I’ve checked all settings like allowing location etc.

Why has this happened and how can I stop it happening again?

also, anyway to recover the gps data as surely it must be somewhere as it knows how far I went!?

Thanks,

Rob