Why does my Average Pace displays as ZERO during middle/end of hike, and after completion? Fenix 5x Sapphire

The actual average pace came out to a little under 1 mile per hour. No Auto-lap/Auto-Pause activated. Using Fenix 5x Sapphire

Here was my activity

I noticed during the middle of the activity, it stopped giving me average pace altogether on my data fields of the watch. What would cause this?