Elevation not correct

My Explore 2 always shows the wrong Elevation at the start, even if i manually calibrate it. It jumps between 200m, then when i go to Calibrate again via GPS it goes to 140m, then again 160m etc. My old Edge 530 never did this, showed the correct elevation. The problem is my rides elevation are a mess, also if i look at the side by side data to the 530 (my partner uses it) it's clean data, on the Explore 2 the elevation jumps up and down all the time on the ride , even if i riding 100m on flat roads, where the gain would be in 1km maybe 5m, it jumps to +-5m the whole 1km.

Is there any fix for this?

The below picture is a side by side ride for 2h!