This issue has happened to me a few times. I was in approach to Auckland Intl. and I selected my NAV1 to be runway 5R and changed the source to NAV1 and activated APPR mode on the A350-900 when I was on the glide slope and the localiser.
I always end up too high as the mode does not descend as much as it should which ends up affecting my landing and I’m not sure why this happens.
It would be great if this issue can be solved.