I just updated my rM1 from 3.11.3.3 to 3.18.1.1, in preparation now that it sounds like toltec will be targeting 3.18 for the next release.
codexctl install rm1_remarkable-production-image-3.18.1.1-rm1-public.swu
The update proceeded fine, but after it finished waiting for the update to complete it never rebooted the tablet. Eventually the install script came up with a request to turn off the update flag, which I let it do. The script then finished without errors.
My tablet had still not rebooted, so I rebooted. It came up with the new version, but the update flag was not turned off (I did it manually).
If there are any logs I could pull from the tablet that would be of use let me know. If this is a known issue please close with a note. I did a search but couldn't find it reported previously.