Guess I took to long to respond.
mtp://Google_Pixel_6_1C061FDF6007QB/Internal%20shared%20storage/DCIM/Camera/IMG_20240519_135018_665.jpg
I think you can see the relevant wiring here, receiver to encoder, encoder to pixhawk. That look right?
https://drive.google.com/file/d/1Naht5cmBwLatELIFnFHqS25F9frhSWP0/view?usp=sharing
Now it occasionally registers input, but it just maxes for a fraction of a second then stops, or does it when I’m not even moving the controls as you can see in that video.
Went back over everything. No dice.
I ordered one of those encoder/receiver combos from the instructions, and another transmitter off Amazon since I can return them if unwanted anyway, so maybe that will do it if the wiring looks right.