Rival GPS mismatch

Having an issue that started with my rival last week.

The GPS distance on the main screen is basically showing either 0 or N/A or a fraction of a mile, both on runs and open water swims.

However the map view shows accurate routing of where I’ve been.

Any reason why the two would be basically taking the same input and showing totally different results?

Tried it on a short bike ride and it appeared to work fine, but now three runs and a swim have all been useless.

Have a triathlon next weekend and would like to know if there is something I should do ahead of that.