Fenix 8 Estimated finish time

Hi all.  I have added estimated finish time (this seems to be the only relevant option. on the watch) to a data field.

Presumably once it knows distance to end from a gps or on the hoof routing, the watch uses average pace to estimate this?

every time I have gone out and tried this, the display is blank here ie no number are shown under EST FINISH TIME

am I doing something wrong or is this yet another Fenix 8 bug?