Offered here as a solve for anyone else who finds this problem (everyone else will probably not understand this, and that’s okay):
I had a functioning installation of TT-RSS being served by Apache, then decided to put a nginx proxy in front of my home websites/servers. Immediately after doing so, I could no longer authenticate with Newsbeuter or Newsboat (a fork of Newsbeuter that is actively maintained).
My nginx setup has all HTTP traffic redirected to HTTPS, as you should, and then it communicated with Apache via HTTP on a different port. And in my Newsboat config, I had this line:
ttrss-url “https://my.tt-rss.install.com”
After messing around with Apache and nginx configurations, I finally stumbled upon the right solution: changing that line in my Newsboat configuration to:
ttrss-url “https://my.tt-rss.install.com”
And now it works just fine.
I’m not sure why changing it to http instead of https made a difference, but it did. So hopefully this helps someone else down the line.
Now I might just update my scripts for Newsbeuter to be more functional with my current flow.