unfortunately I am facing the exact same issue as mentioned by OP. I also tried all the steps described in this thread but did not get it to work.
Any further ideas what this could be? A list of things I tried:
Rebuilding the database from scratch
Running the ConfigSeeder again
./validate.php is clean with no errors
This is a fresh install on Ubuntu 18.04 using only the provided guide from the docs
Similar issue here. I built a test install on some junky hardware about three weeks ago, wanted try importing a few things from observium and test out alerting, no issues related to email. Found some better hardware and completed a fresh install on Friday and have the same “ERROR: no config item” when toggling ‘enable email alerting’ as well as when I try and switch the Geocoding engine away from the default Google Maps. Same error when I toggle “Enable Dynamic graphs.” Both installs were on Ubuntu 18.04 server.