Fenix 6 Pro - Charging During Ultra Issue

Hi All, 

Can't seem to get an answer on line about this one, but a couple of friends have had the same issue.

I recently ran an ultra to half-way (50 miles), and plugged in my Fenix 6 Pro whilst eating.  I went to put the watch back on, to start the second half of the race, and the activity/workout had stopped, and gone back to watch face.  Very annoying, as then had my ultra in two halves.

Not the end of the world I know - but, has anyone else that this issue, and solved it?  As mentioned - a couple of friends have had similar - plug in mid race; goes back to watch face and ends the activity.

With thanks, 

Chris.