GPT-6 Astra suddenly not available in "Chat" side of ChatGPT. Can still see it in "Work" on Pro plan

Users are reporting that GPT-6 Astra is no longer available in the "Chat" section of ChatGPT, both in the Windows and web applications. This issue affects users who were previously having detailed conversations with Astra for weeks. While it has disappeared from the "Chat" side, it is still visible in the "Work" section for those on a Pro plan. Restarting and re-authenticating have not resolved the problem, leaving users wondering about the cause of its sudden disappearance.