Many long-term FECA claimants (as well as SSA recipients) have stopped filing tax returns. If you have not filed a 2019 or 2018 tax return you need to register as a non-filer in order to receive your payment and any payments due for your dependent beneficiaries.
I was just reading an article that suggests that if you do not register by tomorrow, April 22, 2020, you or your dependent beneficiaries may lose entitlement. Here is a link to the tool on the IRS website to take care of registering:
The article after this paragraph has a lot of good information that you should read BEFORE filling in the IRS page as there are common errors that will cause you to lock yourself out of the website or cause delays in your payment. I strongly recommend you read through this first to help familiarize yourself with the process and avoid mistakes that other people have already made: