In normal times it takes up to 16 weeks or more to process an Amended 1040X return. But these are not normal times.
They closed in March and still have limited staff. They just started opening the mail in June that's been stacking up. So you have to keep waiting.
See this IRS page for the latest information
https://www.irs.gov/newsroom/irs-operations-during-covid-19-mission-critical-functions-continue
Then once they start opening the mail, After 3 weeks you can track it here,
https://www.irs.gov/filing/individuals/amended-returns-form-1040-x-/wheres-my-amended-return-1
