What image did you flash? If you used the initramfs image to install, the behavior you are seeing would be expected. Download and install the sysupgrade image using the currently running openwrt flash upgrade process and you should be good.
Ah, thank you for pointing out the expected behavior. I had assumed whatever image I flashed would persist settings. I had downloaded the kernel image here. initramfs it was!
root@OpenWrt:~# dmesg | grep overlayfs
[ 72.905131] overlayfs: upper fs does not support tmpfile.
I will install the sysupgrade image and verify my settings persist.
Yup. I thought so. For certain devices, this is actually part of the upgrade process: stock fimrware > OpenWrt (initramfs) > OpenWrt (squashfs). Once you install the sysupgrade image (which is squashfs), you should be able to save your configuration settings properly.