Just mentioning this here in case someone encounters the same issue.
TL;DR: workaround found for attended sysupgrade of this router.
I was upgrading from an older version 22.03.3-r20028 while also trying to keep my configuration files.
The Luci attended sysupgrade was not resulting in an upgraded version.
The router would thankfully reboot but the Openwrt version would stay the same.
Over ssh a "sysupgrade -v --test /tmp/image.itb" would not bring clarity as no errors were mentioned.
I downloaded the milestone sysupgrade .itb image version 22.03.4 and was able to upload and flash this via Luci and keep the configuration.