Email from Roadrunner.com does not show but server test works

Setting up Thunderbird for the first time so I can use Thunderbird as "aggregator" for all types of email (incl POP3) on both PC and android tablet. It is working for my Gmail account but not for my POP3 account with Roadrunner (aka Spectrum, aka Charter). The POP3 account is most important and I have 2 more addresses there that I also need to monitor. In the settings section for the roadrunner account there is a server test which seems to work but no email shows up in that account in Thunderbird. I am still getting new email directly in the Spectrum setup that I always use. Google AI thinks my setup should work. How should I proceed? Obviously contacting Spectrum is the easy answer but I thought maybe someone easier to contact would know a likely cause. Thanks