It’s an informative video, but it doesn’t specifically address my question. The first few minutes of the video apply to an ILS approach, ie don’t arm LOC if the approach routing will take you across the ILS course. The remainder of the video applies to non-ILS APPR.
The instances I am referring to occurred when flying an ILS approach. The aircraft was in level flight below the glideslope. After arming APPR, the aircraft left altitude and climbed to capture the ILS glideslope.