Yea, I have CISS and it complained every so often about empty cartridges and it has 6 cartridge slots. Switch off & on clears them. But eventually it reports inkpad counter full. It may be the head cleaning cycles, it may just be a time/print thing whatever they call it. Basically they claim that cheap printers (£150 five years ago - cheap?) wear and they count the head cleaning as an arbiter of age (hmmmm) at which point the printer has worn to the point of inaccuracy, they say.
My printer is definitely worn, the evidence is there but it has still is useful within limits. So I may just reset the counter and deal with the replacement in a week or so. I had a candidate (A3ish!) but when I saw it there was a better model which had not been researched (CISS eg).
CISS is a better solution than cartridges emptying when you least expect it, and not having the one you need. Epson's answer is tanks. But not for a printer that does CDs.