Closed topic unresolved: custom MCP connectors cannot coexist with built-in Apps in Developer Mode

I’m seeing a reproducible issue where built-in ChatGPT Apps/connectors disappear or become unavailable after invoking a custom MCP connector in the same conversation. This does not look like an OAuth issue, because both tools work independently. Reproduction steps: 1. Start a new regular ChatGPT conversation. 2. Use a built-in App such as Notion. Notion is visible and works. 3. Invoke a custom MCP connector, in my case a Huawei health-data MCP connector. 4. The custom MCP connector works and returns normal read-only data. 5. Try to use Notion again in the same conversation. Expected behavior: Built-in Apps such as Notion should remain available after invoking a custom MCP connector, or ChatGPT should clearly document that built-in Apps and custom MCP connectors cannot coexist in the same conversation. Actual behavior: After invoking the custom MCP connector, Notion may disappear from the available tool namespace, become unavailable, or the conversation may fail with a “message stream error.” In some attempts, the visible tool/app context refreshes and only the custom MCP tools remain. Additional observations: * Notion works before the custom MCP call. * The custom MCP connector works independently. * The issue appears when switching between built-in Apps and custom MCP tools in the same thread. * Hard refresh does not reliably fix the issue. * This also affects developer workflow, because MCP development often requires using other official Apps such as Notion, GitHub, Gmail, or Hugging Face at the same time. This seems like a ChatGPT Apps / Connectors / MCP tool-registry or app-availability state synchronization bug. I have already escalated this through OpenAI Support and can provide screenshots, timestamps, and conversation details privately if needed.