Based on https://ttlc.intuit.com/community/taxes/discussion/my-1099-misc-includes-income-not-received-until-2017-so-can-i-use-my-qb-income-or-must-i-use-my-1099/00/156510 and other advice, for my 2018 taxes I did include 1099 Income Not Received in 2018, since I received it in 2019.
How do I report that income now that I'm doing my 2019 taxes? Do I just use "Other self-employed income" or is there another way to report it?
Yes, you are correct. You should report this as Other self-employed income in 2019.