This was the same bug reported in another thread – case-sensitive URL matching. If your site URL had any capitalization differences between visits, Remarkbox created separate namespaces and threads for each variant.
URLs and namespace names are now normalized to lowercase, which prevents this. If you’re still seeing the issue, reach out with your domain so we can check for leftover duplicates.
Full details: https://git.unturf.com/engineering/remarkbox/remarkbox/-/blob/main/docs/tickets/1.md