A:AnswerI found the fix, and am happily using third party ink again. Good luck!
https://mattpilz.com/how-to-downgrade-epson-xp-printer-firmware-fix-ink-not-recognized-error-xp-300-to-xp-640/#tablepress-1_wrapper
(the firmware downgrades he directs you to are authentic Epson files, and I haven't had any issues).