uLanding Issues with Arduplane 3.8.0

All,

My goal is to use the Aerotenna uLanding-C1 for the purpose of maintaining AGL and improving landing performance.

Current Configuration:
Pixhawk 2.1: ArduPlane V3.8.0
GCS: Mission Planner 1.3.49 build 1.1.6410.20232
Altimeter: Aerotenna uLanding-C1 (Serial)

I have the uLanding connected to Serial4 (GPS2) of the Pixhawk 2.1.
SERIAL4_PROTOCOL: 12 (uLanding Parameter value)
SERIAL4_BAUD: 115 (uLanding default Baud Rate)

The only parameter I have changed regarding the range-finder functionality is:
RNGFND_TYPE: 11 (uLanding Parameter value)
I have tried adjusting various values related to the upper and lower bounds, but none have seemed to affect readout. See below.

Unexpected Behavior:
Upon connecting Mission Planner to the Pixhawk, SonarRange reads "0". If I move the altimeter around, 1-3 three similar windows open (??), and the SonarRange value is populated. In most cases, a value of 6.35 (cm) is displayed regardless of orientation and obstructions before the altimeter. On occasion, sporadic (erroneous) values are displayed.

Debugging:
I have used the provided python scripts to manually read out serial data from the uLanding - the values roughly correspond to appropriate distances, though I've considerable concern regarding the consistency of the data. The distances have a considerable number of outliers in the positive direction.

Side Question:
Has anyone implemented uLanding variants with a CAN/I2C option in Ardupilot?

I was hoping someone with a similar configuration utilizing the uLanding might give advice on the proper configuration (parameters) or known issues with my configuration.
Current theories:

PH2.1 cannot sustain 115 kbaud on Serial4? When I tried lowering to 9600 baud, the value reset itself to 115 kbaud on next startup and connect cycle.
Some parameter related to the abundance of laser analog/PWM altimeters is interfering with the value?

See below [Forum Link] for an example of the issue (including mystery window) and a copy of my parameters.

NOTE: This question was originally asked here https://discuss.ardupilot.org/t/aerotenna-ulanding-extensive-issues/20062 as I figured it was a general Ardupilot issue. There, it was recommended that I consult here, as the problem may be driver related.