Board Auto-Due Dates + List-Specific Fields Issue

[DJ]

Hi Trello Support,
On our Premium board, new cards in all lists auto-set due dates to exactly 6 days from creation (e.g., Jan 10 → Jan 16), but:
• No Butler rules (checked Rules/Scheduled/Due date commands - empty)
• No Power-Ups (disabled Card QR Code, empty list)
• No templates (checked/deleted)
• No extensions (incognito test same)
• No automation logs
• New boards clean, copies inherit issue
Additionally need list-specific custom fields (4 left lists → Production/Closed retain unique fields) in one board.
Screenshots attached. Board ID/link: [paste URL]. How to:
1. Stop auto-due dates?
2. List-specific fields visibility?
Thanks!