SITL: spurious waypoints in mission

All that follows on SITL on macOS.

I am observing spurious waypoints in SITL missions, that are not followed but appear on console.

Consider a simple mission such as:
QGC WPL 110
0 1 0 16 0 0 0 0 33.74113111 -118.3746000 178 1
1 0 3 22 0 0 0 0 33.74116111 -118.3746000 1.00 1
2 0 3 201 0 0 0 0 33.74111111 -118.3750000 1.00 1
3 0 3 16 0 0 0 0 33.74111111 -118.3747222 4.00 1
4 0 3 21 0 0 0 0 33.74119111 -118.3746000 0.00 1

If executed with
./sim_vehicle.py -v ArduCopter -f quad -l 33.74111111,-118.374600,178,270 --use-dir=BigW --console
and observed in QGC, after landing this appears on console:
APM: Mission: 3 Land
waypoint 3
APM: SIM Hit ground at 0.556849 m/s
APM: Disarming motors
APM: Mission: 1 SetROI
APM: Mission: 2 WP
DISARMED
waypoint 2
Bold lines seem spurious and not followed on QGC.

Changing waypoints 1 and 3 (Relative) to Terrain (3->10):
QGC WPL 110
0 1 0 16 0 0 0 0 33.74113111 -118.37460000 178 1
1 0 10 22 0 0 0 0 33.74116111 -118.37460000 1.00 1
2 0 3 201 0 0 0 0 33.74111111 -118.37500000 1.00 1
3 0 10 16 0 0 0 0 33.74111111 -118.37472222 4.00 1
4 0 3 21 0 0 0 0 33.74119111 -118.37460000 0.00 1
the console shows:
APM: Mission: 3 Land
waypoint 3
APM: SIM Hit ground at 0.550490 m/s
APM: Disarming motors
APM: Mission: 1 SetROI
APM: Mission: 2 WP
APM: Failsafe: Terrain data missing
APM: Reached command #2
APM: Mission: 3 Land
DISARMED
and in adition, since mixing Relative (third parameter 3) and Terrain (third parameter 10) seems a mystery, “Failsafe: terrain data missing” is heard and appears on QGC.

See this video (4K) with captures:

Should this happen so?

Anybody there???

Same on SITL Ubuntu 20.04. Video:

Same on Fedora 33. Video: