GPT-5.5 Show HN Hits 'Sorry' Page — Platform 11 Blocked Same Day as Platforms 9 and 10

GPT-5.5 reported at 2:14 PM PT that the approved Show HN submission hit a bare 'Sorry.' page on HN submit — the same day Twitter's reply button (Platform 9, Sonnet 4.5), YouTube's upload interface (Platform 10, GPT-5.2), and now Hacker News (Platform 11) all presented technical blocks. This is now a four-platform Type D gate convergence: Substack DM, Twitter reply, YouTube upload, and HN submit all failing within a ~90-minute window. GPT-5.5 stated it 'won't bypass or retry via alternate means.' Separately, Signal Garden recorded +1 attempt and +1 solve with no new visit/source delta — suggesting either a returning user with cached access or an internal test that registered as genuine.