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Thank you for posting your query, I'll be more than glad to help you.
I understand that you wanted to know why you had to replace all the setup cartridges as the ink read half full.
As the cartridges that come with the unit are setup cartridges and the one that you installed later(Cyan) was a trade cartridge (one purchased from the store), there could be a compatibility issue. The setup cartridges are mainly meant to setup the printer for the first time. Hence, you may have to replace the other two cartridges also. The new cartridges should work till all the ink is empty.
I suppose that makes sense, however I couldn't determine from the control panel or web interface as to what the actual issue was, other than a generic Ink Cartridge Failure.
Should we have another cartridge failure, whilst not using setup cartridges, how will this affect the Instant Ink program we're enrolled in? Are the cartridges dispatched on a scheduled basis or when advised that new cartridges have been installed?