After playing around with some settings and doing some uninstall/reinstall work, I have an even stronger suspicion that this is a chrome mobile specific issue.

Uninstalling updates and reverting back to the factory installed version allows Known to ask for permission to use location and then finds the location properly. Updating thereafter to the most recent version of chrome mobile then prevents Known from finding my location (and it doesn't ask for permission to use location either.)

Two other mobile browsers don't seem to have any issues.