. Here is a potential new issue or limitation for some LOS devices trying to deal with Moto partition madness:
MiX XDA Stable 6.35.2 on Moto X4 running LOS 16 (Android 9) with LOS SU cannot write to / (root) or /system/etc but can write to /data/data.
Attached log spans one or more attempts or MiX sessions to create a new file in /system/etc. I tested before and after installing MiX busybox but forget which one the log captured (result was the same). A comparative test in Total Commander seemed to fail around the RW remount but I'm just going by a UI indicator there, no log.
I've found no app yet which can write to /system/etc in LOS 16 on this device and even attempts to use recovery to create symlinks (for Adway) to /data/data (which can be written to) fail. I'm not seeing this as a MiX issue but hoping there might be some way to work around it.
[EDIT] Discovered later that using Magisk instead of native LOS SU allows write access to root, so this is clearly an issue between LOS and its own SU.