Strange behaviour on (very) long run. Now last activity not showing on watch.

I have a Fenix 7S Pro.

Yesterday I did a 4.5 hour run. Halfway through the watch stopped the activity by itself. I only noticed after ~8 mins and restarted the activity. 

At the end of the run, I stopped the activity and pressed save, then the watch restarted itself before showing any of the run information. 

When it turned back on I went to the last activity widget,  the glance was still showing my run 4 days ago. At this point I was panicking thinking my marathon effort was lost forever.

However, going into the last activity app, the first activity is still the run from 4 days ago, but scrolling down the 'previous' activity is my 4.5 hour run, phew!

For some reason it's stuck like this. The long run has uploaded to connect, but it's not contributing to my training status, endurance score, or any of those metrics.

Is there a size limit on activities for those metrics? Is there anyway to fix this?

Thanks