Problems with updating orders by API

We've been updating orders with APIs for 2 or more years and only in the last few weeks have noticed that our updates have started failing. This is especially problematic when ready dates or requested delivery dates change and our transportation department is not seeing that change come through.

I have been using "Edit an order after it has been dispatched" but have tried "Revise an Order by Customer and Order ID" and "Update customer's order by ID"

These are Classic APIs, v1.

Are they all still supported? has anything changed? are there different rules in place on updating orders? have any of the endpoints changed?

Also, what's the best way to hear of changes?