I had a Fenix 5S up to 1 month ago, and it would count the laps without any issues. I switched to a Fenix 5S Plus, one month ago. For the first 3 weeks the swimming lap accuracy was spot one. Since Satursday it adds 10 laps after the first dozen,
It counts perfectly from 1 to 12
At 12 t shows 22
At 22 it shows 42
etc etc and 72 it shows 142.
That is on the watch. Also on the watch the distance is shown as a multiple of the laps shown and the pool distance.
However, when I sync the data back to Garmin Connect I see the correct distance.
I believe the issue for me started happenning with the latest firmware update (4.0.0.0) !!!
I hope Garmin fix this soon because this bug spoils all the fund in swimming....