Swimtime 36h+ added? Calories?

Hello there

I did a short swim this morning of 500m in a 25m pool and when I was done it showed around 4k+ kcal burned and added somewhere 36h+ to the workout. The elapsed time etc still is correct, but why does this keep happening?

The watch is brand new and I have now disabled the auto-rest. Will this solve that problem, did you guys experience the same issue?

Thanks so much in advance, I'm very new to this and want accurate stats!