I've already got a ticket in for this with support but I just want to check if any other users are having this issue.
I noticed that since 05/02/19 all amazon FBM (we only do FBM) orders are coming down with no VAT.
Totals are right just if you look in the order XML i'm seeing TAX as 0 (this on UK/EU orders for me as I don't sell outside the EU on Amazon)
I have raised a ticket for you. Please provide me with order examples there.