The last time i filed was 2018. I received the first stimulus, but not this one. My transcripts only show for the first stimulus being deposited as of yesterday. ??

The second stimulus check is based on your 2019 income tax return and since you did not file one, you will need to file a 2020 income tax return to receive the stimulus payment. 

• The IRS advises people that if they don’t receive the full Economic Impact Payment they should file their 2020 tax return electronically and claim the Recovery Rebate Credit on their tax return to get their payment and any refund as quickly as possible.