The IRS has not processed many paper tax returns since the pandemic started.
Go to this IRS website for information - https://www.irs.gov/newsroom/irs-operations-during-covid-19-mission-critical-functions-continue
We’re experiencing delays in processing paper tax returns due to limited staffing. If you already filed a paper return, we will process it in the order we received it.
Do not file a second tax return or contact the IRS about the status of your return.
Keep checking the status of the amended tax return at this IRS website - https://www.irs.gov/filing/wheres-my-amended-return