When I attempt to add this site: https://minorpieces.uk/ or /feed/ the site gets stuck at “Fetching new feed” – I’ve tried waiting it out, clearing cache/cookies, etc.
The feed validates: https://validator.w3.org/feed/check.cgi?url=https%3A%2F%2Fminorpieces.uk%2Ffeed%2F
I’ve added a few others for testing with no issue.