Terrain following using LiDAR - failsafe: terrain data missing

ArduCopter
1

I have a LiDAR Lite V3HP on a DJI 450 and I’m trying to do terrain following. Been having multiple issues:

  1. When I graph the liDAR data in Mission Planner tuning, it shows it dropping out at 10-12 meters. The Garmin spec says good up to 40M? Flying over grass, so it may not be ideal.
  2. Since I’m losing LiDAR at 10M, I set RNGFND_ALT_MAX to 10M. And then my understanding is that above the 10M, it will switch to baro.

I program a mission flying at 15m. If the LiDAR gets out of range and/or gives bad data, I thought it should switch to baro and maintain roughly 15m, however it just keeps climbing. Either I get a “Failsafe-terrain data missing” and RTL or it climbs until it hits the geofence at 50m and does an RTL.

Is my understanding of the expected behavior wrong, or am I doing something wrong?

Thank you in advance for any comments!