Yes amending will stop the advance CTC while it takes 6 months or more to process. If your ONLY thing that needed to change on the return was the unemployment then the IRS is doing that automatically for anyone eligible for more of a refund due to the exclusion ... they do NOT want amended returns for this item.
Not everyone will get more of a refund after the exclusion ... so you CAN use the amendment program to see what the change will eventually be if any ... just do NOT file the 1040X.
