HACS not loading custom component - Stuck on Checking repository

I am trying to add a custom component in HACS and it’s getting stuck right at the start on “Checking repository”. No other output in the log files, no indication that it fails (add button stays pressed). Any ideas what could be causing this? Below is literally all I get:

2021-08-23 22:33:58 DEBUG (MainThread) [custom_components.hacs] <Plugin theozzierat/bom-radar-card> Checking repository.