Hello,
It appears the problem was with the site I was using the TOTP generator with (https:/passpack.com), and not with the Enpass application. I was later (the next day) able to re-add a seed and generate proper numeric codes. It should not matter, but I experienced the issue with the Windows 10 Universal, Windows standalone, and Android versions of the application (all are using a synced password database).
Thank you for the quick follow-up; I really appreciate it.