The IRS closed their processing centers in March because of the Covid-19 pandemic, and stopped processing mailed tax returns. They recently started to reopen the processing centers and process the mailed tax returns, but they have limited staff and a huge backlog. They have millions of pieces of mail that they haven't even opened. So it will be quite a while before your 2018 tax return is processed or any status information is available.
The IRS web site says the following.
"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."
You mailed it right? The IRS closed in March for several months. They didn't start opening the mail until June. An IRS spokesperson recently said that they have about 11 million pieces of unopened mail. The IRS says....."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." So it may take longer if you mailed in June or later. 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