Hello,
i dont know if this is normal, but my Garmin Fenix 6X pro current pace shows + - 20-30 seconds, but at the end my average tempo maybe is correct. If my pace is 4 min/km, first for 5 seconds it shows 3:40, then the next 5 seconds it shows 4:20 and so on. I run with constant pace all the time.
Also if i set my target pace to be 3:55-4:00, 70% of the time my watch alerts me for high pace even if the pace is slower.
Even when i walk, my pace is all over the place. Its like that on almost all activities.
Do you have such problem?