@tmomas, I've checked many versions: 19.07.1, 19.07.0, 18.06.8, 18.06.7, 18.06.6, 18.06.0. In all these versions problem is as I wrote above.
Version 17.01.7 (lede-17.01.7-ramips-rt305x-3g-6200n-squashfs-sysupgrade.bin) works perfect and save settings after reboot.
login as: root
root@192.168.1.1's password:
BusyBox v1.25.1 () built-in shell (ash)
. .. _________
. . /. . . . /\. . . _. . ___ ___. ___
.. /. LE. . /. \. . | |. | __|.. \| __|
. /. . DE. /. . \.. | |__| _|| |) | _|
/________/. LE. \. |____|___|___/|___|. . . . . . . . . . . lede-project.org
\. . . . \.. DE /
. \. . LE. \. . /. -----------------------------------------------------------
.. \. DE. . \. /. . Reboot (17.01.7, r4030-6028f00df0)
. . \________\/. . -----------------------------------------------------------
root@OpenWrt:~# mount
/dev/root on /rom type squashfs (ro,relatime)
proc on /proc type proc (rw,nosuid,nodev,noexec,noatime)
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,noatime)
tmpfs on /tmp type tmpfs (rw,nosuid,nodev,noatime)
/dev/mtdblock7 on /overlay type jffs2 (rw,noatime)
overlayfs:/overlay on / type overlay (rw,noatime,lowerdir=/,upperdir=/overlay/upper,workdir=/overlay/work)
tmpfs on /dev type tmpfs (rw,nosuid,relatime,size=512k,mode=755)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,mode=600)
debugfs on /sys/kernel/debug type debugfs (rw,noatime)
root@OpenWrt:~# df -h
Filesystem. . . . . . . . Size. . . Used Available Use% Mounted on
/dev/root. . . . . . . .. 2.3M. . . 2.3M. . . .. 0 100% /rom
tmpfs. . . . . . . . . . 14.1M. . 420.0K. .. 13.6M.. 3% /tmp
/dev/mtdblock7. . . . . 384.0K. . 240.0K. . 144.0K. 63% /overlay
overlayfs:/overlay. . . 384.0K. . 240.0K. . 144.0K. 63% /
tmpfs. . . . . . . . .. 512.0K. . . .. 0. . 512.0K.. 0% /dev
root@OpenWrt:~# free
. . . . . .. total. . .. used. . .. free. .. shared. . buffers. .. cached
Mem:. . . .. 28780. . . 16624. . . 12156. . . . 420. . .. 1896. . .. 5708
-/+ buffers/cache:. . .. 9020. . . 19760
Swap:. . . . . . 0. . . . . 0. . . . . 0
root@OpenWrt:~#
Is it any chance to fix this?
I saved these logs from SSH console for all softs which I tested.
If you want more information tell me.