Missing ascent when riding a course using the Tacx Neo 2T and the Fenix 6X Pro

The last couple of weeks (2-3), I do not get the right elevation (the course elevation) when riding a course from the Fenix 6X Pro with the Tacx Neo 2T.
To me, it seemed like it was determining elevation using the barometer instead of the course elevation.
While the gradient and thus the resistance was working as it was supposed to, the elevation and thus the ascent didn't change despite going up the mountain.

Before this used to work like a charm, it has only been this last couple of weeks, so probably has come with a recent update of the watch.