Adding initialUrl and options paramer leads to 404

According to the documentation, https://cloudflare.com/apps/short-io/install?initialUrl=kostenko.name should pre-populate domain name, but it returns 404. Same is with youtube application, which is used as an example. Same is with options parameter - adding it returns error 404 instead (both for my app and example app from the documentation)

Documentation URL: https://www.cloudflare.com/apps/developer/docs/promoting-your-app/preview-links